Add development tests

[Vlad118]

These may be useful to reference for development. They ensure that new features work correctly and may potentially be reused to ensure that game updates or other features do not break them.

I can make a folder structure for this and submit some of my own tests first.

[DaddelZeit]

We should also change how kissmp VLua extensions are loaded. The current solution blocks running the Lua client mod as unpacked as it fails to load all extensions properly.