Add: [Script] GetAirportNumHelipads (#12085)

Adds a function for Scripts to get the number of helipads of an airport type.

Change: forcefully enable prefixing logs with date (#11930)

Additionally, add the log-level to the log message.

Change: replace per-AI "start_date" with a global "competitors_interval" (#10653)

The per-AI "start_date" is a lot of custom code, and was rarely
used in the way it was meant.

While at it, also ported this part over to the new timer system.

Fix: [Script] ScriptBase::Rand() return value was between -MIN(int32) and MAX(int32) (#10443)

Also ensure the parameters for ScriptBase::RandRange() and ScriptBase::Chance() are in [0-MAX(uint32)] range

Add: [Script] ScriptCargo::GetName, to get the human readable name of a cargo (#8544)

Of course this translates into AICargo.GetName() for AIs and
GSCargo.GetName() for GameScripts.

Fix #7656: destroying a tunnel/bridge now first removes the tracks for cost calculation

This means that for rail tunnel/bridges, the rail is first sold,
and the tunnel/bridge is destroyed after. This means destroying
tunnels/ bridges now often makes you money, instead of costing.

Similar, with road/tram tracks. Destroying a road+tram
tunnel/bridge now costs the same amount of money as first
removing the tram tracks and than destroying the road
tunnel/bridge. Especially as tram tracks generate money when
removing, this is a noticeable difference.

Fix: prefix the Nth vehicle with "#" when ungrouped

This is for consistency; most other objects add a # to indicate
it is the Nth of that object, except for Trains / RVs / Ships /
Aircrafts.
This becomes painfully apparent with unnamed vehicles in groups,
which do get a "#".

Codechange: move regression outside of bin and make it work via CMake script

The tst_stationlist savegame had to be changed to start the correct
AI. In the old setup, all regression AIs had the same name, which
made it impossible to run both regressions in parallel. With the new
setup this is possible.

Although all files are available to run the regression, it won't
really work till CMake is introduced (which will happen in a few
commits from here)