[Matrix] Update mangling to use paramterized vendor ext type syntax.

The Itanium CXX ABI grammer has been extended to support parameterized
vendor extended types [1].

This patch updates Clang's mangling for matrix types to use the new
extension.

[1] https://github.com/itanium-cxx-abi/cxx-abi/commit/b359d28971bdb961dd9b61bd0ef8c884452b4740

Reviewed By: rjmccall

Differential Revision: https://reviews.llvm.org/D91253