Add Wireframes for 2D Mode

[yosimba2000]

I'm working in the 2D mode, and have a subdivided plane. Unfortunately, I cannot see the actual subdivisions since wireframes are unavailable.

Please make wireframes available in 2D.

My use case: I'm making a shader that displaces vertices on the mesh, and I need to visibly see the vertices.

[Calinou]

This makes sense, but note that in the Compatibility rendering method, wireframes must be generated in advance. This is automatically done while in the editor in 3D (RenderingServer.set_debug_generate_wireframes()), so the same functionality would have to be added in 2D.

In the meantime, you could run Godot through RenderDoc and get a wireframe view this way.