Add config option allowing map loader to prefer RPG Maker files

[ianling]

Adds a new boolean to the player config: PreferEasyRpgMapFiles (default: true)

This makes the map loader attempt to load EasyRPG map files first, and fall back to RPG Maker map files on errors. Since it defaults to true, this PR retains the existing behavior of the EasyRPG Player, which attempts to load EasyRPG map files first.

I just wanted a way to turn this behavior off in my game, as it creates issues with my VCS setup (essentially, a pre-commit hook that runs lcf2xml on all the files in the project).

QA steps I tried:

• New option set to the default of 1 (true) in config:
  • .emu and .lmu present -> Player loads .emu ✅
  • .emu present, .lmu not present -> Player loads .emu ✅
  • .emu not present, .lmu present -> Player loads .lmu ✅
  • .emu and .lmu not present -> Player crashes with expected error (Error: Loading of Map Map0001.lmu failed. -- notice it loaded the .lmu last) ✅
• New option set to 0 (false) in config:
  • .emu and .lmu present -> Player loads .lmu ✅
  • .emu present, .lmu not present -> Player loads .emu ✅
  • .emu not present, .lmu present -> Player loads .lmu ✅
  • .emu and .lmu not present -> Player crashes with expected error (Error: Loading of Map Map0001.emu failed. -- notice it loaded the .emu last) ✅
• New option missing from config uses default value (1) ✅

[carstene1ns]

Seems a valuable addition for developers at least.
Though exposing this in the UI is debatable IMHO.
The end user does not benefit from this and can be confused.

[ianling]

Completely agree. To clarify, it is not exposed in the UI. I am not sure what is missing from this PR that is causing it to not appear in the UI, but I guess it's a happy accident that it does not appear.

[Ghabry]

To make it appear you must add it in window_settings.cpp but I agree that it is better to not show it

[Ghabry]

Could you rename mapIsEasyRpgFile to map_is_easyrpg_file to match our naming convention for local variables. Besides this looks good to me.

[ianling]

Done