Remove custom pipeline

[rparrett]

I was curious to see if this was possible and it was, so I'll open this up for discussion.

The benefits would be that we get to delete a bunch of code that is usually painful to migrate, and maybe Bevy will implement batching for Mesh2d some day.

The main hacky bit is that the MaterialMesh2dBundle needs a white color material for the vertex colors to work properly (bevy's default is fuchsia and the color is multiplied) and I'm currently just creating that every time remeshing happens. At the very least, that could be cleaned up so that it only happens on shape creation.

But I'm hoping for something cleaner. That probably involves using our own material/shader, which should be a lot less involved than a full-on custom pipeline. I'll investigate that soon.

I'm also not sure if it's possible to get lyon to tesselate with the correct winding order, so I just reversed the indices.

[rparrett]

Here's a branch with a custom ShapeMaterial
https://github.com/rparrett/bevy_prototype_lyon/tree/shape_material
This re-introduces a bit of rendering boilerplate, but it looks pretty reasonable, actually.

And expanding that with texture support:
https://github.com/rparrett/bevy_prototype_lyon/tree/shape_material_uvs
I need to investigate whether the texture "flag" is totally necessary, and figure out what the UX for adding a texture to a shape should be.

[rparrett]

My current plan is to rebase and use the ShapeMaterial option and leave supporting textures as future work.

This actually got a bit simpler after bevyengine/bevy#7514.

[Nilirad]

This actually got a bit simpler after bevyengine/bevy#7514.

That's good. I remember culling was one of the problems I faced with the original renderer that induced me to create a custom pipeline, since Lyon seemed to not to do winding correctly.

[Nilirad]

Looks good! Make sure to appease clippy and I think we're ready to go.