[X86][SLH] Add VEX and EVEX conversion instructions to isDataInvariantLoad

[X86][SLH] Add VEX and EVEX conversion instructions to isDataInvariantLoad

-Drop the intrinsic versions of conversion instructions. These should be handled when we do vectors. They shouldn't show up in scalar code.
-Add the float<->double conversions which were missing.
-Add the AVX512 and AVX version of the conversion instructions including the unsigned integer conversions unique to AVX512

Differential Revision: https://reviews.llvm.org/D49313

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@337066 91177308-0d34-0410-b5e6-96231b3b80d8