Remove: setting "no_http_content_downloads" (#12058)

As we now use HTTPS, it is very likely this will work on most systems.
For systems that do have HTTPS blocked, it will fail instantly,
and it will fallback to TCP anyway. That makes this setting no longer
very useful.

Codechange: automatic adding of _t to (u)int types, and WChar to char32_t

for i in `find src -type f|grep -v 3rdparty/fmt|grep -v 3rdparty/catch2|grep -v 3rdparty/opengl|grep -v stdafx.h`; do sed 's/uint16& /uint16 \&/g;s/int8\([ >*),;[]\)/int8_t\1/g;s/int16\([ >*),;[]\)/int16_t\1/g;s/int32\([ >*),;[]\)/int32_t\1/g;s/int64\([ >*),;[]\)/int64_t\1/g;s/ uint32(/ uint32_t(/g;s/_uint8_t/_uint8/;s/Uint8_t/Uint8/;s/ft_int64_t/ft_int64/g;s/uint64$/uint64_t/;s/WChar/char32_t/g;s/char32_t char32_t/char32_t WChar/' -i $i; done

Fix: reset content download progress to zero if falling back to TCP

Otherwise this chain of events can happen:
- You already have a (partial) file downloaded
- You start the download, and HTTP fails
- This resets the download progress to the current size of the file
- The TCP download starts at a very large value (UINT32_MAX - filesize)

It now resets to 0% done when any negative value is being given.
As added bonus, we no longer have to query how much was already
downloaded.

Add: use https:// for content-service connections (#10448)

This requires the use of WinHTTP (for Windows) or libcurl (for all
others except Emscripten). Emscripten does not support http(s)
calls currently.

On Linux it requires ca-certificates to be installed, so the HTTPS
certificate can be validated. It is really likely this is installed
on any modern machine, as most connections these days are HTTPS.

(On MacOS and Windows the certificate store is filled by default)

Reminder: in case the http(s):// connection cannot be established,
OpenTTD falls back to a custom TCP-based connection to fetch the
content from the content-service. Emscripten will always do this.

Add: support filtering content entries for patchpacks (#9541)

This changes nothing for us, but allows patchpacks to add the
right pieces of code to start filtering content entries on patchpack
only entries.

Fix #9535: Maintain a reverse dependency map of network content (#9538)

Fixes performance issues with dependency lookup when retrieving
content list from the content server.

Feature: allow setting (game) coordinator and content server connection strings using environment variables

OTTD_COORDINATOR_CS for the game coordinator defaults to coordinator.openttd.org:3976
OTTD_CONTENT_SERVER_CS for the content server defaults to content.openttd.org:3978
OTTD_CONTENT_MIRROR_CS for the content mirror server defaults to binaries.openttd.org:80

Codechange: [Network] split CloseSocket and CloseConnection more clearly (#9261)

* Codechange: [Network] split CloseSocket and CloseConnection more clearly

- CloseSocket now closes the actual OS socket.
- CloseConnection frees up the resources to just before CloseSocket.
- dtors call CloseSocket / CloseConnection where needed.

Codechange: remove pointless close call due to resolving virtual functions statically in destructors

In the destructors of many of the network related classes Close() is called, just like the
top class in that hierarchy. However, due to virtual functions getting resolved statically
in the destructor it would always call the empty Close() of the top class.
Document the other cases where a virtual call is resolved statically.

Codechange: use connection_string in favour of NetworkAddress (#9197)

We now resolve the connection_string to a NetworkAddress in a much
later state. This means there are fewer places constructing a NetworkAddress.

The main benefit of this is in later PRs that introduce different types
of NetworkAddresses. Storing this in things like NetworkGameList is
rather complex, especially as NetworkAddress has to be mutable at all
times.

Additionally, the NetworkAddress is a complex object to store simple
information: how to connect to this server.

Fix: Start the inactivity-timeout for the content server only after the connection has been established. (#8530)

When connecting took long due to the first N resolve-addresses timing out, OpenTTD would immediately close the connection, without sending anything.

Fix: Remove unnessary reference to suppress warning (#8337)

Apple Clang version 12 (bundled with Xcode 12) complaints about copying
small objects in range loop (-Wrange-loop-analysis introduced by -Wall).
This warning can be easily avoided by removing the reference from
the const pointer type.

Add: support for emscripten (play-OpenTTD-in-the-browser)

Emscripten compiles to WASM, which can be loaded via
HTML / JavaScript. This allows you to play OpenTTD inside a
browser.

Co-authored-by: milek7 <me@milek7.pl>

Fix: Crash due to use of invalid iterator in ClientNetworkContentSocketHandler

In particular this crash can be observed when using the
bootstrap GUI to download the base graphics.

In ClientNetworkContentSocketHandler::OnReceiveContentInfo
ClientNetworkContentSocketHandler::callbacks is iterated, using an iterator
cb->OnReceiveContentInfo() is called (cb is of type BootstrapAskForDownloadWindow)
This calls new BootstrapContentDownloadStatusWindow()
This inherits from BaseNetworkContentDownloadStatusWindow
The constructor of which calls _network_content_client.AddCallback(this)
This reallocates the std::vector which is being iterated in ClientNetworkContentSocketHandler::OnReceiveContentInfo
This results in iter being invalid, and an assertion failure occurs shortly
afterwards due to its use in the next iteration of cb->OnReceiveContentInfo()

Adjust all locations where ClientNetworkContentSocketHandler::callbacks
is iterated to avoid problematic behaviour

Remove: ENABLE_NETWORK switch

This switch has been a pain for years. Often disabling broke
compilation, as no developer compiles OpenTTD without, neither do
any of our official binaries.

Additionaly, it has grown so hugely in our codebase, that it
clearly shows that the current solution was a poor one. 350+
instances of "#ifdef ENABLE_NETWORK" were in the code, of which
only ~30 in the networking code itself. The rest were all around
the code to do the right thing, from GUI to NewGRF.

A more proper solution would be to stub all the functions, and
make sure the rest of the code can simply assume network is
available. This was also partially done, and most variables were
correct if networking was disabled. Despite that, often the #ifdefs
were still used.

With the recent removal of DOS, there is also no platform anymore
which we support where networking isn't working out-of-the-box.

All in all, it is time to remove the ENABLE_NETWORK switch. No
replacement is planned, but if you feel we really need this option,
we welcome any Pull Request which implements this in a way that
doesn't crawl through the code like this diff shows we used to.

Fix fdc2e85: Double close of file handles

When unpacking downloaded content, the downloaded .gz file was being opened with `fopen`, the OS file handle given to zlib, and then afterwards zlib told to close the file.

But the `FILE *` object was never closed with `fclose`, meaning the stdio library would have a hanging file object, whose file handle was now invalid or referred to a different file. This caused asserts during shutdown with Microsoft's C library in debug mode.

Fix this by properly duplicating the OS handle and `fclose`ing the `FILE *` object, before giving the handle to zlib.