Improve errors about #[deprecated] attribute

[m-ou-se]

This change:

1. Turns #[deprecated] on a trait impl block into an error, which fixes Deprecation attribute on trait impl block is accepted but has no effect #78625;
2. Changes these and other errors about #[deprecated] to use the span of the attribute instead of the item; and
3. Turns this error into a lint, to make sure it can be capped with --cap-lints and doesn't break any existing dependencies.

Can be reviewed per commit.

---

Example:

struct X;

#[deprecated = "a"]
impl Default for X {
    #[deprecated = "b"]
    fn default() -> Self {
        X
    }
}

Before:

error: This deprecation annotation is useless
 --> src/main.rs:6:5
  |
6 | /     fn default() -> Self {
7 | |         X
8 | |     }
  | |_____^

After:

error: this `#[deprecated]' annotation has no effect
 --> src/main.rs:3:1
  |
3 | #[deprecated = "a"]
  | ^^^^^^^^^^^^^^^^^^^ help: try removing the deprecation attribute
  |
  = note: `#[deny(useless_deprecated)]` on by default

error: this `#[deprecated]' annotation has no effect
 --> src/main.rs:5:5
  |
5 |     #[deprecated = "b"]
  |     ^^^^^^^^^^^^^^^^^^^ help: try removing the deprecation attribute