This commit renames the `types.hh` file to `brushes.hh` as an attempt to
make brush implementations more independent and begin to unwind and
remove much of the logic in `sculpt.cc`.
As a first step, this moves the node mask calculation exposed for the
plane brush into `plane.cc` and exposes the function header into
`types.hh`.
Pull Request: https://projects.blender.org/blender/blender/pulls/137020
84f29a0e72