Rollup merge of #161341 - adwinwhite:overflow-fcw-chain, r=lcnr,adwinwhite

be more permissive wrt overflow and and improve diagnostics

This builds on https://github.com/rust-lang/rust/pull/160632

Previously we only showed a single root goal for the FCW. It was difficult to find out how the goal overflowed.
We display a proving chain now which should help users identify relevant types or auto traits.

This will affect perf for crates emitting the FCW. E.g. `calimero-store` goes from 4.7s -> 5.7s in local testing since it emits thousands of FCWs internally. The FCW is a mitigation of future hard error and authors are expected to resolve it so it's probably acceptable. It doesn't affect crates without the FCW.

r? lcnr