Wireframe and Thick-Line Rendering in WebGPU

Demo: https://potree.org/permanent/wireframe_rendering/ (requires at least Chrome 112)

Render an indexed triangle model as mesh, wireframe, wireframe with thick lines, or quads without the need to generate additional buffers for line rendering.

Uses vertex pulling to let the vertex shader decide which vertices to load, which allows us to render indexed triangle meshes as wireframes or even thick-wireframes.