[Proof of concept] Recover from struct literals with placeholder path

[fmease]

I'm surprised my naive approach seems to work but it feels more than hacky (skipping name resolution entirely). I hope to gather some feedback for how to make this more robust and a bit cleaner and for how to resolve the various FIXME(fmease)s I added.

Not sure if I will continue this work by the way, it was a fun experiment on a Saturday evening. Of course, it would be awesome if this landed in some way or another :)

Fixes #98282. Doesn't address #105398 yet.

r? diagnostics

[compiler-errors]

If you want to chat about this approach, happy to, but I've removed the S-waiting-on-review since not sure if you want input or not.

[bors]

:umbrella: The latest upstream changes (presumably #124277) made this pull request unmergeable. Please resolve the merge conflicts.