[NFC] Cleanup and sort hlsl_intrinsics.h (#72414)

This is just a simple cleanup of hlsl_intrinsics.h. I've broken this
into two commits to make it easier to follow during review. The first
commit replaces the `__attribute__` annotations with preprocessor macros
to make it easier to read the function declarations. The second commit
sorts the function declarations.

Function declarations are sorted by function name alphabetically, then
grouped by base element type. The declarations within each group are
sorted in increasing order by number of elements, and the groups
themselves are sorted by increasing element size. For elements of the
same size they are then sorted by signed integers, then unsigned
integers then floating point.