Auto merge of #145314 - estebank:issue-135589-all, r=Nadrieril

Tweak output of missing lifetime on associated type

Follow up to rust-lang/rust#135602.

Previously we only showed the trait's assoc item if the trait was local, because we were looking for a small span only for the generics, which we don't have for foreign traits. We now use `def_span` for the item, so we at least provide some context, even if its span is too wide.

```
error[E0195]: lifetime parameters or bounds on type `IntoIter` do not match the trait declaration
   --> tests/ui/lifetimes/missing-lifetime-in-assoc-type-4.rs:7:18
    |
7   |     type IntoIter<'a> = std::collections::btree_map::Values<'a, i32, T>;
    |                  ^^^^ lifetimes do not match type in trait
    |
   ::: /home/gh-estebank/rust/library/core/src/iter/traits/collect.rs:292:5
    |
292 |     type IntoIter: Iterator<Item = Self::Item>;
    |     ------------------------------------------ lifetimes in impl do not match this type in trait
```

Given an associated item that needs a named lifetime, look at the enclosing `impl` item for one. If there is none, look at the self type and the implemented trait to see if either of those has an anonimous lifetime. If so, suggest adding a named lifetime.

```
error: in the trait associated type is declared without lifetime parameters, so using a borrowed type for them requires that lifetime to come from the implemented type
  --> $DIR/missing-lifetime-in-assoc-type-2.rs:5:17
   |
LL |     type Item = &T;
   |                 ^ this lifetime must come from the implemented type
   |
help: add a lifetime to the impl block and use it in the self type and associated type
   |
LL ~ impl<'a> IntoIterator for &'a S {
LL ~     type Item = &'a T;
   |
```

Move the previous long message to a note and use a shorter primary message:

```
error: missing lifetime in associated type
  --> $DIR/missing-lifetime-in-assoc-type-1.rs:9:17
   |
LL | impl<'a> IntoIterator for &S {
   |     ---- there is a named lifetime specified on the impl block you could use
...
LL |     type Item = &T;
   |                 ^ this lifetime must come from the implemented type
   |
note: in the trait the associated type is declared without lifetime parameters, so using a borrowed type for them requires that lifetime to come from the implemented type
  --> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
help: consider using the lifetime from the impl block
   |
LL |     type Item = &'a T;
   |                  ++
```

r? `@Nadrieril`

Author: bors