This pull request adds the ability for users to specify input samples
on a per brush basis. The existing field in the main `Paint` struct
forces all brushes of a particular tool type to use the same value.
A new field was added to the `Brush` struct to allow for this value
to be specified there instead, and a corresponding unified value in
`UnifiedPaintSettings` has been created to allow users to use the
same value across all brushes.
Addresses #108109
Pull Request: https://projects.blender.org/blender/blender/pulls/117080
a2b3fe5e01