Support translating C++ deprecated attributes as ObsoleteAttribute

[PathogenDavid]

• [ ] Recognizing the attribute (I believe all come through as an attribute of CX_AttrKind_Deprecated
  • [ ] GCC-style __attribute__((deprecated))
  • [ ] MSVC-style __declspec(deprecated)
  • [ ] MSVC-style #pragma deprecated (Might not work with Clang, it's not listed on the attribute reference.)
  • [ ] C++14-style [[deprecated]]
• [ ] Extract the deprecation message
• [ ] Attach the deprecation state/message to declarations. (https://github.com/InfectedLibraries/Biohazrd/issues/24 might be applicable here.)
• [ ] Add emitting the attribute to the C# output generator

[PathogenDavid]

If it turns out that fixing this requires AttributedTypes to be made available, make sure to properly resolve https://github.com/InfectedLibraries/Biohazrd/issues/130 when fixing this.