8371: Don't use HirDisplayWrapper when displaying SourceCode r=matklad a=Veykril
The issue was basically that when displaying for `DisplayTarget::SourceCode` some `hir_fmt` functions would create `HirDisplayWrapper`s which would then `fmt` these triggering the Display panic since `fmt::Display` can't fail the same way as `HirDisplay`. Simple fix is to just use `hir_fmt` directly. Should probably write that down somewhere in source, looking for a good spot to put that right now.
Fixes#8077, Fixes#8370
Co-authored-by: Lukas Wirth <lukastw97@gmail.com>