[New Feature] Write saved games to a sub-directory

[Rampastring]

Description:

To keep the main directory clear, most mods prefer it when the game writes its saved games to a sub-directory. The CnCNet client is also coded to read saved games from the Saved Games sub-directory.

Additional Files:

CnCNet ts-patches implementation: https://github.com/CnCNet/ts-patches/blob/master/src/mods/saved_games_in_subdir.asm