Expose mod.yaml content to localisation.

[RoosterDragon]

Mod metadata, load screens and mod content is all now sourced from ftl files, allowing these items to be translated.

Translations are now initialized as part of ModData creation, as currently they are made available too late for the usage we need here.

The "modcontent" mod learns a new parameter for "Content.TranslationFile" - this allows a mod to provide the path of a translation file to the mod which it can load. This allows mods such as ra, cnc, d2k, ts to own the translations for their ModContent, yet still make them accessible to the modcontent mod.

CheckFluentReference learns to validate all these new fields to ensure translations have been set.

[PunkPun]

ra crashes on startup

Exception of type `System.NullReferenceException`: Object reference not set to an instance of an object.
   at OpenRA.TranslationProvider.GetString(String key, IDictionary`2 args) in /GitHub/OpenRA/OpenRA.Game/TranslationProvider.cs:line 41
   at OpenRA.ExternalMods.Register(Manifest mod, String launchPath, IEnumerable`1 launchArgs, ModRegistration registration) in /GitHub/OpenRA/OpenRA.Game/ExternalMods.cs:line 126

[RoosterDragon]

ra crashes on startup

This seems to be relted to external mod registrations. I've removed the "Title" field since we may not be able to provide the translated title - as we haven't loaded the translations. This means GameServer.ModTitle might not be human-readable any more since I've had to use the mod ID in some places instead. Not sure what we can reasonably do here - the "human-readable" text might not be available in the required language anyway.

[pchote]

Mod registrations are local to the current computer, so its fine to take the current language and write localised strings directly into the metadata.

[RoosterDragon]

Okay it's good that the text will match. However that still leaves the problem with the mod not being loaded, thus no translations, thus no ability to write out the translated title anyway.

[PunkPun]

Can't launch ./launch-dedicated.sh

OpenRA/OpenRA.Game/Manifest.cs(60,17): error CS0102: The type 'ModMetadata' already contains a definition for 'Title' [OpenRA/OpenRA.Game/OpenRA.Game.csproj]

[RoosterDragon]

Can't launch ./launch-dedicated.sh

That looks like a local merge error. I've rebased onto bleed if that is helpful.

[PunkPun]

changelog