The CMake buildsystem should be completely reviewed to properly match
what is done by SCons, instead of making its own arbitrary decisions on
how godot-cpp should be compiled.
Currently the SCons setup doesn't include warning options, so CMake
shouldn't either. Options similar to upstream Godot's SCons setup could
be added, and then replicated for CMake.
Changes the `<godot/gdextension_interface.h>` include to simply
`<gdextension_interface.h>`.
Refactor and better document the SCons and CMake logic around setting
the paths to the header and API JSON file.
Rémi Verschelde
Fabio Alessandrelli
bruvzg
Nicolás Carrasco
O01eg