Sculpt: add Topology Rake, to align edges along brush while painting.

Sculpt: add Topology Rake, to align edges along brush while painting.

This helps to generate cleaner topology and define sharp features for dynamic
topology. Best used on relatively low-poly meshes, it is not needed as much
for high detail areas and has a performance impact.

Differential Revision: https://developer.blender.org/D4189