Auto merge of #114811 - estebank:impl-ambiguity, r=wesleywiser

Show more information when multiple `impl`s apply

- When there are `impl`s without type params, show only those (to avoid showing overly generic `impl`s).
```
error[E0283]: type annotations needed
  --> $DIR/multiple-impl-apply.rs:34:9
   |
LL |     let y = x.into();
   |         ^     ---- type must be known at this point
   |
note: multiple `impl`s satisfying `_: From<Baz>` found
  --> $DIR/multiple-impl-apply.rs:14:1
   |
LL | impl From<Baz> for Bar {
   | ^^^^^^^^^^^^^^^^^^^^^^
...
LL | impl From<Baz> for Foo {
   | ^^^^^^^^^^^^^^^^^^^^^^
   = note: required for `Baz` to implement `Into<_>`
help: consider giving `y` an explicit type
   |
LL |     let y: /* Type */ = x.into();
   |          ++++++++++++
```

- Lower the importance of `T: Sized`, `T: WellFormed` and coercion errors, to prioritize more relevant errors. The pre-existing deduplication logic deals with hiding redundant errors better that way, and we show errors with more metadata that is useful to the user.

- Show `<SelfTy as Trait>::assoc_fn` suggestion in more cases.
```
error[E0790]: cannot call associated function on trait without specifying the corresponding `impl` type
  --> $DIR/cross-return-site-inference.rs:38:16
   |
LL |     return Err(From::from("foo"));
   |                ^^^^^^^^^^ cannot call associated function of trait
   |
help: use a fully-qualified path to a specific available implementation
   |
LL |     return Err(</* self type */ as From>::from("foo"));
   |                +++++++++++++++++++     +
```

Fix #88284.

compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs

@@ -27,7 +27,7 @@ use std::iter;
 
 pub enum TypeAnnotationNeeded {
     /// ```compile_fail,E0282
-    /// let x = "hello".chars().rev().collect();
+    /// let x;
     /// ```
     E0282,
     /// An implementation cannot be chosen unambiguously because of lack of information.