Auto merge of #97313 - cjgillot:ast-lifetimes-anon, r=petrochenkov

Resolve function lifetime elision on the AST

~Based on rust-lang/rust#97720

Lifetime elision for functions is purely syntactic in nature, so can be resolved on the AST.
This PR replicates the elision logic and diagnostics on the AST, and replaces HIR-based resolution by a `delay_span_bug`.

This refactor allows for more consistent diagnostics, which don't have to guess the original code from HIR.

r? `@petrochenkov`

Author: bors