[VE] Add vector mask operation instructions

Add VFMK/VFMS/VFMF/ANDM/ORM/XORM/EQVM/NNDM/NEGM/PCVM/LZVM/TOVM
isntructions.  Add regression tests too.  Also add new patterns
to parse VFMK/VFMS/VFMF mnemonics.

Reviewed By: simoll

Differential Revision: https://reviews.llvm.org/D90297