Always compute coroutine layout for eagerly emitting recursive layout errors
Detect recursive coroutine layouts even if we don't detect opaque type recursion in the new solver. This is for two reasons:
1. It helps us detect (bad) recursive async function calls in the new solver, which due to its approach to normalization causes us to not detect this via a recursive RPIT (since the opaques are more eagerly revealed in the opaque body).
* Fixes https://github.com/rust-lang/trait-system-refactor-initiative/issues/137.
2. It helps us detect (bad) recursive async functions behind AFITs. See the AFIT test that changed for the old solver too.
3. It also greatly simplifies the recursive impl trait check, since I can remove some jankness around how it handles coroutines.
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