This PR implements the source mapping for .NET compilers (C#, F#, VB.NET
and IL), supports CoreCLR, Crossgen2 and NativeAOT compilers.
- Add a parser that walks ECMA-335 metadata and Portable PDB sequence
points to build IL-offset-to-source mappings for .NET methods
- Load PDBs emitted by the .NET compiler after building the dll, and
then save the source mapping in the result
- Extend the .NET asm parser to match disassembly method signatures,
including generic types, generic methods, and inline root offsets, so
emitted asm lines inherit the correct source locations
- Use debug info emitted by the JIT `INLRT @ 0x##` as anchors to match
the offset
Showcase:

