Rollup merge of #126985 - Mrmaxmeier:dwarf-embed-source, r=davidtwco

Implement `-Z embed-source` (DWARFv5 source code embedding extension)

Implement rust-lang/compiler-team#764 MCP which adds an unstable flag that exposes LLVM's [DWARFv5 source code embedding](https://dwarfstd.org/issues/180201.1.html) support.