Add missing Projection constructor with 16 real_t values

[aaronfranke]

When GDExtension generates bindings, it creates C++ code based on the API JSON. Values are serialized into literals constructed with numbers matching the value, for example, Vector3(0, 1, 0). This includes default values for function parameters. Projection default values are serialized like Projection(1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1). However, Godot is missing a constructor for Projection, so the generated C++ code doesn't compile:

I encountered this problem when the CI checks for godot-cpp failed to compile with my 4D module, because one of the bound methods includes a Projection default value, which cannot be constructed, as seen in the above image. This wasn't a problem in the engine before because the engine doesn't have any Projection default values in parameters.

Note: I believe to fix the exact problem, it only needs to be added to godot-cpp (see godotengine/godot-cpp#1742). However, we should make the same change in the engine for consistency. I also added this to C# but not GDScript since we do the same for other similar types (Transform2D/Transform3D/Basis).

[Repiteo]

I could've sworn we already had a bulk constructor like this for Projection, but it really is only for the types you mentioned. We probably should have GDScript binds for this type of constructor, but that should be handled in a dedicated PR.

Either way, everything checks out!

[Repiteo]

Thanks!