[HLSL] Vector Usual Arithmetic Conversions (#110195)
HLSL has a different set of usual arithmetic conversions for vector
types to resolve a common type for binary operator expressions.
This PR implements the current spec proposal from:
https://github.com/microsoft/hlsl-specs/pull/311
There is one case that may need additional handling for implicitly
truncating vector<T,1> to T early to allow other transformations.
Fixes #106253
Re-lands #108659
