[lld] [LLD][COFF] Store reference to SymbolTable instead of COFFLinkerContext in InputFile (NFC) (PR #119296)

[Martin Storsjö via llvm-commits]

https://github.com/mstorsjo approved this pull request.

This bit looks ok. I feel there's some level of inconsistency left around what is passed to the `InputFile` subclass constructors though.

https://github.com/llvm/llvm-project/pull/119296