Demangling support for class type non-type template parameter extensions.

The extensions in question are described in:
https://github.com/itanium-cxx-abi/cxx-abi/issues/47
https://github.com/itanium-cxx-abi/cxx-abi/issues/63

Differential Revision: https://reviews.llvm.org/D90003

GitOrigin-RevId: bec968cbb367dd03439c89c1d4ef968ef662d7c0
2 files changed