Rollup merge of #41489 - estebank:trait-bounds-diagnosstic, r=arielb1

Make unsatisfied trait bounds note multiline

Make diagnostic note for existing method with unsatisfied trait bounds
multiline for cleaner output.

```
  = note: the method `count` exists but the following trait bounds were not satisfied:
          `[closure@../../src/test/compile-fail/issue-36053-2.rs:17:39: 17:53] : std::ops::FnMut<(&_,)>`
          `std::iter::Filter<std::iter::Fuse<std::iter::Once<&str>> [closure@../../src/test/compile-fail/issue-36053-2.rs:17:39: 17:53]> : std::iter::Iterator`
```

Before:

```
  = note: the method `count` exists but the following trait bounds were not satisfied: `[closure@../../src/test/compile-fail/issue-36053-2.rs:17:39: 17:53] : std::ops::FnMut<(&_,)>`, `std::iter::Filter<std::iter::Fuse<std::iter::Once<&str>>, [closure@../../src/test/compile-fail/issue-36053-2.rs:17:39: 17:53]> : std::iter::Iterator`
```