This PR adds builtin shaders for drawing points. Using `FLAT_COLOR`,
`SMOOTH_COLOR`, `UNIFORM_COLOR` can lead to undesired behavior
on Metal and Vulkan backends. To ensure future compatibility this PR
adds `POINT_FLAT_COLOR` and `POINT_UNIFORM_COLOR`.
The point size can be set using `gpu.state.point_size_set`.
Pull Request: https://projects.blender.org/blender/blender/pulls/139583
c56a855b9f