Add MSVC demangler correctness fixes and generated test corpus

[plafosse]

This is quite a substantial refactor of the msvc demangler which solves pretty much all known de
mangler accuracy issues.

Major changes:

• Demangling now is backed by the DemangledTypeNode like gnu3 is. The purpose is
  to provide an abstraction layer between c++ features and binary
  ninja's type objects.
• Substantial performance increase I think around 3x what it was before
  this is due to cutting down on extraneous string copies and type object allocations
• Substantial accuracy fixes. The most substantial of which is accurate scoping
  of back references.
• Lots and lots of other small fixes. This commit could have been about 100 commits but
  I didn't feel that adding all those commits would be helpful in understanding what's
  actually going on here.

Fixes:

• Windows Visual C++ name demangler fails in some cases #7466
• Support for demangled variable names #3535
• demangle_ms bugs/improvements #1653
• Large number of symbols in some Microsoft x86_64 PE files fail to get demangled #1605
• Demangling error #1546

[plafosse]

I realized that bb9e720 and 7bfbb87 have regressed performance. And this needs some more changes so I'm converting it back to a draft :\