This removes the need for the geometry shader and the
workaround path for Metal.
Note that creating 2 batches for each stroke might become
a bottleneck in bigger scenes. But currently the bottleneck
is always be the fill algorithm. It can be optimized further
if needed.
Rel #127493
Pull Request: https://projects.blender.org/blender/blender/pulls/129274
3035fd1c36