[codeview] Improve names of types in scopes and member function ids

[codeview] Improve names of types in scopes and member function ids

We now include namespace scope info in LF_FUNC_ID records and we emit
LF_MFUNC_ID records for member functions as we should.

Class names are now fully qualified, which is what MSVC does.

Add a little bit of scaffolding to handle ThisAdjustment when it arrives
in DISubprogram.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@273358 91177308-0d34-0410-b5e6-96231b3b80d8