Cleanup: remove IConsoleWarning/IConsoleError helpers

Both did not support format parameters, so in many places IConsolePrint(CC_ERROR, "message") was used with a style different from what IConsoleError would do.

Change: unify the style of console error messages and convert to fmt

Always start with a capital, do not add "ERROR: " in front of it.

Change: not performing a command is worthy of an error, not a warning

If a command cannot be executed for whatever reason, it makes no sense to call it a warning. Something has been done wrong.
Also make writing of these error message consistent while changing their "type".

Fix #9361, a2051ba: [Network] Off by one in CanWriteToPacket

Previously it did not allow writing a byte to a packet that was of size limit - 1 anymore.

Fix #9362: Hover in online players window was slightly too big (#9364)

This causes graphical glitches at the bottom of the window.

Update: Translations from eints
norwegian (bokmal): 10 changes by Anolitt
korean: 9 changes by telk5093
russian: 9 changes by Ln-Wolf
finnish: 10 changes by hpiirai
spanish: 8 changes by MontyMontana
french: 9 changes by glx22

Change: Skip creating a RealSpriteGroup when there is only one result.

This avoids checking RSG for empty sets every time they are evaluated.
This might alter behaviour in cases of a malformed NewGRF file.

Codechange: Deduplicate ResolveReal() for resolvers that don't use real sprite groups.

This may change behaviour when multiple loading/loaded stages are provided, as the various copies checked in different orders, however only one result is expected in these cases anyway.

Update: Translations from eints
hindi: 67 changes by ritwikraghav14

Fix #9348, 4d74e51: don't try to sell shares of spectators (#9349)

"new_owner" can be INVALID_OWNER, and as INVALID_OWNER ==
COMPANY_SPECTATORS, we could end up trying to sell shares of
nobody.

Add: '-X' option to ignore global folders in the search path (#9341)

This is extreme useful for automated testing. Without this, OpenTTD
will always look in your personal-dir (like ~/.local/share/openttd
or %USER%\Documents\OpenTTD). For most users this is exactly what
we want, that there is a shared place for all their files.

However, for automated testing this is rather annoying, as your
local development files influence the automated test. As such,
'-X' counters this, and only gives the local folders. This is
especially useful in combination with '-x' and '-c'.

Add: adhere the autosave_on_exit setting for Null videodriver (#9343)

This is especially useful for automated-testing, to make a save
when the game quits while using "-vnull:ticks=N".

Codechange: rename SL_LST to SL_REFLIST to highlight the "reference" part

You can easily mistake SlList / SL_LST to be a list of SL_VAR, but
it is a list of SL_REF. With this rename, it hopefully saves a few
people from "wtf?" moments.

Codechange: refactor SlDequeueHelper to work with unsigned and be more generic

Future additions will start using it for std::list too.

Codechange: move GetVariableAddress inside SlObjectMember

Also move it to static, as nobody else is using it.

Update: Translations from eints
spanish (mexican): 2 changes by absay

Update: Translations from eints
german: 1 change by Wuzzy2
spanish: 1 change by ilyabakhlin

Fix: compatible NewGRFs in crash-log reported wrong md5 (#9340)

The text suggests it reports the original md5, but it does in fact
report the replaced md5. Now it reports both.

Codechange: make [Save|Load]Settings() behave more like other Save/Load code (#9335)

Prepare the full description and send it to SlObject. This does
require some code to be able to read to a SLE_VAR_NULL, like strings
etc, as there is no way to know their length beforehand.

Codechange: merge guiflags and flags in settings .ini files

It was rather confusing which one was for what, especially as some
SaveLoad flags were settings-only. Clean up this mess a bit by
having only Setting flags.

Codechange: move SLF_NO_NETWORK_SYNC into settings

It is a settings-only flag, so don't pollute SaveLoad code with it.

Codechange: move SLF_NOT_IN_SAVE into settings

It is a settings-only flag, so don't pollute SaveLoad code with it.

Update: Translations from eints
english (us): 1 change by 2TallTyler
catalan: 5 changes by J0anJosep

Codechange: Remove FOR_ALL_CHUNK_HANDLERS

Co-Authored-By: Patric Stout <truebrain@openttd.org>

Update: Translations from eints
spanish (mexican): 1 change by absay
latvian: 2 changes by osprinkis

Update: Translations from eints
korean: 1 change by telk5093
dutch: 1 change by Afoklala
french: 1 change by MalaGaM

Update: Translations from eints
korean: 1 change by telk5093

Codechange: rename SettingGuiFlag to SettingFlag (#9332)

It is a lovely organicly grown enum, where it started off with
GUI-only flags, and after that a few flags got added that can be
considered GUI-only (the GUI disables/enables based on them), to
only have flags added that has nothing to do with the GUI.

So be less confusing, and rename them to what they do.

Additionally, I took this opportunity to rename 0ISDISABLED to
reflect what it really does.

Codechange: use "[[maybe_unused]]" instead of a wide variety of other ways we had

While at it, replace OTTD_ASSERT with WITH_ASSERT, as this
is always set if assert() is valid. No matter if NDEBUG is set
or not.

Update: Translations from eints
swedish: 1 change by joeax910

Codechange: C++-ify lists for SaveLoad (#9323)

Basically, this changes "SaveLoad *" to either:
1) "SaveLoadTable" if a list of SaveLoads was meant
2) "SaveLoad &" if a single entry was meant

As added bonus, this removes SL_END / SLE_END / SLEG_END. This
also adds core/span.hpp, a "std::span"-lite.

Update: Translations from eints
japanese: 1 change by scabtert

Update: Translations from eints
korean: 2 changes by telk5093
russian: 1 change by Ln-Wolf
finnish: 1 change by hpiirai
portuguese: 1 change by azulcosta
portuguese (brazilian): 1 change by Vimerum

Codechange: use setting name instead of index for CmdChange(Company)Setting (#9306)

This is mostly done as there are now constraints on settings.ini you might not
expected. For example, conditional settings always have to come last, as otherwise
they would influence the index.