Support new "Windows 10 on ARM" platform (and drop Windows RT)

[Ghabry]

Windows 10 on ARM will run native desktop apps without ugly test-signing hacks. And WinRT is dead, dropping it is fine imo.

There is a x86 Emulator built-in but this is a waste of CPU cycles (but EasyRPG Player will probably run fine through it considering how low our requirements are).

Should be possible via vcpkg.

[Ghabry]

Already 5 years again... vcpkg succesfully compiled our dependencies for ARM64 so will likely work fine.

Imo ARM can be omitted. Bet the market share of windows on ARM is really low and 32 bit ARM is slowly dying.