[llvm] [Object] Beginnings of SFrame parser and dumper (PR #147294)

[James Henderson via llvm-commits]

https://github.com/jh7370 commented:

Is there a specification that can be pointed to in the commit description? It's a bit hard to review a parser without actually knowing what the specification is :)

https://github.com/llvm/llvm-project/pull/147294