Intel hardware intrinsic API change

[fiigii]

According to the second hw intrinsic API review meeting https://github.com/dotnet/apireviews/tree/master/2018/Hardware-Intrinsics-Intel, we need to change some intrinsic APIs and their implementation

1. Redesign SSE4.2 STTNI intrinsic
   • issue https://github.com/dotnet/corefx/issues/30373
   • PR [No Merge]Adding SSE4.2 STTNI intrinsic APIs coreclr#19958
2. 64-bit only intrinsics
   • issue https://github.com/dotnet/coreclr/issues/18744
   • PR Expose 64-bit only hardware intrinsic in nested classes coreclr#20146
3. Improve StaticCast
   • PR Move the various helper intrinsics to be implemented on the S.R.Intrinsics.Vector types coreclr#20147
   • solution
   1. exploding frequently-used intrinsic on more base-types Add all integer overloads for AlignRight/BlendVariable and unsigned overloads for MultiplyLow coreclr#19420
   2. move StaticCast and some other helpers into vector classes, and rename StaticCast to As.
4. New intrinsic requests
   • issues https://github.com/dotnet/coreclr/issues/19071, https://github.com/dotnet/coreclr/issues/19271, https://github.com/dotnet/coreclr/issues/18459, https://github.com/dotnet/corefx/issues/32075
   • waiting for concrete API proposals and reviews
5. Missing and incorrect APIs
   • PRs Add pointer overloads for Avx2.BroadcastScalarToVector128 coreclr#20055, Fix inconsistent Intel hardware intrinsic APIs coreclr#19949
6. Remove generic Intel hardware intrinsic and explode them on all the supported types
   • issue https://github.com/dotnet/coreclr/issues/20057

[fiigii]

@CarolEidt @tannergooding @eerhardt @jkotas @AndyAyersMS @mikedn @terrajobst

[fiigii]

Moved to CoreFX repo https://github.com/dotnet/corefx/issues/32721, closing here.