Rollup merge of #138019 - obi1kenobi:pg/pretty-print-more-attrs, r=compiler-errors

Pretty-print `#[deprecated]` attribute in HIR.

Pretty-print `#[deprecated]` attribute in a form closer to how it might appear in Rust source code, rather than using a `Debug`-like representation.

Consider the following Rust code:
```rust
#[deprecated]
pub struct PlainDeprecated;

#[deprecated = "here's why this is deprecated"]
pub struct DirectNote;

#[deprecated(since = "1.2.3", note = "here's why this is deprecated")]
pub struct SinceAndNote;
```

Here's the previous output:
```
#[attr="Deprecation{deprecation: Deprecation{since: Unspecifiednote:
suggestion: }span: }")]
struct PlainDeprecated;

#[attr="Deprecation{deprecation: Deprecation{since: Unspecifiednote:
here's why this is deprecatedsuggestion: }span: }")]
struct DirectNote;

#[attr="Deprecation{deprecation: Deprecation{since: NonStandard(1.2.3)note:
here's why this is deprecatedsuggestion: }span: }")]
struct SinceAndNote;
```

Here's the new output:
```rust
#[deprecated]
struct PlainDeprecated;

#[deprecated = "here's why this is deprecated"]
struct DirectNote;

#[deprecated(since = "1.2.3", note = "here's why this is deprecated"]
struct SinceAndNote;
```

Also includes a test for `#[diagnostic::(..)]` attributes, though their behavior is not changed here. I already wrote the test, so I figured it probably won't hurt to have it.

Related to discussion in #137645.

r? `@jdonszelmann`

0 files changed, 0 insertions, 0 deletions