Adds a "Select by Attribute" operator as mentioned in the discussion in
#105317. This is done in 4.0 to limit the breaking aspect of the removal
of face maps. The selection storage functionality is replaced by boolean
attributes. We already have a way to control the data in the boolean
attribute with the "Set Attribute" operator, but we didn't have a way to
convert the attribute into a selection.
This operator works on the active attribute if is a boolean attribute
and isn't on the face corner domain. It adds to the existing selection
similar to other existing operators.
While this behavior can be recreated as a node tool, we add it as a
builtin operator here to avoid limitations of the new node-based
tool system and to make the late-in-the-release-cycle change safer.
Hans Goudey