fix: impl Trait desugaring in trait objects' assoc constraints

[randomicon00]

Issue: #96529

Right now, the tasks that are done:

• saving the desugaring into an ìmpl_trait_context`.
• add impl_trait_id to rust_ast::AssocConstraint.

In progress:
The next tasks are a break out of what I am trying to accomplish. A bit different from the original tasks in order to be as precise as possible and help with mentoring.

• create visit_assoc_constraint in def_collector and create the local def id there by matching with UniversalInDyn context.
• replace the desugar_to_impl_trait with the associated constraint check.
• remove the enum rust_ast_lowering::ImplTraitContextand add the vector to LoweringContext.
• use that vector in the relevant places and retrieve it through the use of with_hir_id_owner.

Not started yet.

• create a ResolverAstLowering::get_impl_trait_context(LocalDefId) to access the ImplTraitContext value.
• fix method parameter documentation for lower_fn_decl.

[rust-highfive]

r? @wesleywiser

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[randomicon00]

r? @cjgillot

[bors]

☔ The latest upstream changes (presumably #97598) made this pull request unmergeable. Please resolve the merge conflicts.

[cjgillot]

Suggested change

	//| ImplTraitContext::UniversalInDyn(item_def) => {
	| ImplTraitContext::UniversalInDyn(item_def) => {

This is the correct behaviour here.

[bors]

☔ The latest upstream changes (presumably #98106) made this pull request unmergeable. Please resolve the merge conflicts.

[Dylan-DPC]

@randomicon00 what's the status of this?

[randomicon00]

@Dylan-DPC Will have an update in the next two weeks.
For now, I still have parts of desugaring logic in hir.

[Dylan-DPC]

@randomicon00 any updates on this?

[Dylan-DPC]

Closing this as inactive. Feel free to reöpen this pr or create a new pr if you get the time to work on this. Thanks