Add support for web builds (using emscripten at least)

[Klaim]

Godot games can be built as wasm, in which case the gdextension they use must be built as wasm files. Currently this is not tested but I suspect it will not work immediately as there are speciifc options to handle, like Godot 4.3's new support for switching on/off "threading" (which when turned off helps with publishing web games without having to handle support of haredArrayBuffer on the server side).