[FEATURE] Add gamedata as lua modules root.

[Neloreck]

Changes

• Adding string script to use $game_data$ as lua modules root
• Allows usage of multiple files with custom game scripts using built-in lua tools without globals/patched GSC interceptors

Limitations

• Lua does not check DB files so scripts called with require should be under gamedata/* root
• Approach with monkeypatching does not work with locals/requires, but it is great for usage with tools like https://github.com/TypeScriptToLua/TypeScriptToLua