Move tests out of the shipped library

[ericoporto]

It's a bit too soon for the things in the public API but some internals could be tested.

I think I would just use my own tap module for that.

Right now, the code at least have some expect(bool expr) so at least it can do some sanity checks at runtime.

[ericoporto]

I actually added some minor tests, I obviously can add more, I need to move ImGi tests to a separate module.

I think it's possible to import the internals on other file and use it because AGS kinda don't care as long as things link fine at runtime.

I could even add an extra room and then rename it to room1.crm and use it to run the tests in the CI.