Remove generic Intel hardware intrinsic and explode them on all the supported types

[fiigii]

According to the latest API review meeting, we determined that hardware intrinsic should explicitly be exploded on all the supported types (e.g., Vector256<int>, Vector128<long>, Vector128<short>, Vector256<float>, etc). This also makes it clear when/if support for new types (e.g., Half) are added in the future that they aren't supported in the older ISAs. But we may be able to have generic helper intrinsic (like SetAllVector256<T>).

@CarolEidt @tannergooding @eerhardt

[tannergooding]

CC. @terrajobst

[Wraith2]

Are api reviews still recorded or noted somewhere?

[fiigii]

@Wraith2 https://github.com/dotnet/apireviews/tree/master/2018/Hardware-Intrinsics-Intel