[AVX512] Added VPBROADCAST{BWDQ} (Load with Broadcast Integer Data from General Purpose Register) encodings for AVX512-BW/VL subsets
Added encoding tests.
        


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223787 91177308-0d34-0410-b5e6-96231b3b80d8