Reland "[DebugInfo][clang][DWARF5]: Added support for debuginfo generation for defaulted parameters

in C++ templates."

This was reverted in 802b22b5 due to
missing .bc file and a chromium bot failure.
https://bugs.chromium.org/p/chromium/issues/detail?id=1057559#c1
This revision address both of them.

Summary:
This patch adds support for debuginfo generation for defaulted
parameters in clang and also extends corresponding DebugMetadata/IR to support this feature.

Reviewers: probinson, aprantl, dblaikie

Reviewed By: aprantl, dblaikie

Differential Revision: https://reviews.llvm.org/D73462