Remove "Invert Visible" from the face sets menu, since those concepts
are no longer tied together, except for some convenience features to
toggle visibility of some face sets.
On the code side, the `SCULPT_OT_face_set_invert_visibility` operator
is replaced by `PAINT_OT_visibility_invert`. It inverts vertex visibility
instead of face visibility, which mostly has the same results, except
for multires sculpting where it no longer "downgrades" visibility to
base mesh faces.
Hans Goudey
53418fc3a1