Add better default spans for the Ty impl of QueryKey

[Zoxc]

This add default spans for Ty in its implementation of QueryKey. This is useful so we can get spans for the layout_of query which shows up in cycle errors.

[rustbot]

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[JohnTitor]

r=me once you fix the failure above

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[Zoxc]

Maybe this could just use characteristic_def_id_of_type if we're aiming to remove DefId from ty::Alias. @WaffleLapkin @lcnr Would there be a way to find the DefId / Span associated with the alias if that happens?

[lcnr]

most aliases will still have an associated DefId, we just want to be able to add ones which don't in the future

[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[rustbot]

The Miri subtree was changed

cc @rust-lang/miri

[Zoxc]

@rustbot ready

[JohnTitor]

r? lcnr for further review

[oli-obk]

specifically for projection aliases I think what users usually need is the impl, not the trait decl

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[Zoxc]

We probably can't find those without potentially causing query cycles though, which we must avoid in this context.