This commit takes the namespaces used in `sculpt_intern.hh` and splits
them into their own header files to better logically separate data and
avoid pulling in so many transitive dependencies by needing to include
`sculpt_intern.hh`
Actual removal of `sculpt_intern.hh` from other files is pending
further cleanup of the methods contained within.
A quick summary of the other changes included in this commit:
* `enum` to `enum class` cleanup for enums to enable forward
declarations
* `FilterCache` default destructor to allow forward declaration of
other dependent `struct`s contained in `unique_ptr`s
* Cleanup of unused headers
* Move `SculptBoundary` into the `boundary` namespace
* Move misc brush method forward declarations into `types.hh`
For a given `.cc` file that corresponds to a specific `.hh` file, the
header has been placed at the very top to try and ensure that the
needed data is self contained.
Forward declaration is preferred in most of these files outside of the
templates, classes, and structs in BLI headers.
---
Manual testing done:
- Enter Sculpt mode and perform strokes
- Use automasking for some strokes
- Use mesh filter
Pull Request: https://projects.blender.org/blender/blender/pulls/126443
852b3dbff3