[OpenMP][Opt] Annotate known runtime functions and deduplicate more

This adds ~27 more runtime calls to the OpenMPKinds.def file, all with
attributes. We deduplicate 16 of those automatically in function =
thread scope. And we annotate all of them automatically during the
OpenMPOpt discovery step. A test with all omp_XXXX runtime calls to
track annotation coverage is included.

Reviewed By: JonChesterfield

Differential Revision: https://reviews.llvm.org/D69984