GlobalISel: Work on improving stock set of legality predicates
I get confused by a lot of the predicate names here, since I would
assume they apply to vectors as well. Rename to reflect they only
apply to scalars.
Also add a few predicates AMDGPU uses that should be generally useful.
Also add any() to complement all. I've wanted to use this a few times
but then worked around it not being there.