Blender Git Loki

Sculpt: Expose Edit Face Set as a tool

Previously the way to use this operations was using the shortcut Ctrl +
W and Ctrl + Alt + W, which was not very discoverable and it was
limiting the amount of options that can be added to the operator.Now the
same functionality of the operator is available as a tool, which will
make easier to add other editing operations and options without adding
more entries to the keymap.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D8545