[OpenMP][NFC] Use OMPInteropInfo in the OMPDeclareVariantAttr attribute

In preparation for allowing the prefer_type list in the append_args clause,
use the OMPInteropInfo in the attribute for 'declare variant'.

This requires adding a new Argument kind to the attribute code. This change
adds a specific attribute to pass an array of OMPInteropInfo. It implements
new tablegen needed to handle the interop-type part of the structure. When
prefer_type is added, more work will be needed to dump, instantiate, and
serialize the PreferTypes field in OMPInteropInfo.

Differential Revision: https://reviews.llvm.org/D132270