[JITLink][COFF] Initial COFF support.

Adds initial COFF support in JITLink. This is able to run a hello world c program in x86 windows successfully.

Implemented
- COFF object loader
- Static local symbols
- Absolute symbols
- External symbols
- Weak external symbols
- Common symbols
- COFF jitlink-check support
- All COMDAT selection type execpt largest
- Implicit symobl size calculation
- Rel32 relocation with PLT stub.
- IMAGE_REL_AMD64_ADDR32NB relocation

Reviewed By: lhames

Differential Revision: https://reviews.llvm.org/D128968