Improve the suggestion's syntax in `collapsible_match` check

[sobolevn]

Description

Today I got a collapsible_match warning in a project I am working on, this was the code it was raising on:

enum Token {
    Name,
    Other,
}

struct Error {
    location: u32,
    token: Option<Token>,
}

fn add_anon_function_hint(err: Option<Error>) {
    if let Some(Error { token, .. }) = err {
        if let Some(Token::Name) = token {
            println!("Name error");
        }
    }
}

It looked like this:

warning: this `if let` can be collapsed into the outer `if let`
  --> compiler-core/src/example.rs:13:9
   |
13 | /         if let Some(Token::Name) = token {
14 | |             println!("Name error");
15 | |         }
   | |_________^
   |
help: the outer pattern can be modified to include the inner pattern
  --> compiler-core/src/example.rs:12:25
   |
12 |     if let Some(Error { token, .. }) = err {
   |                         ^^^^^ replace this binding
13 |         if let Some(Token::Name) = token {
   |                ^^^^^^^^^^^^^^^^^ with this pattern, prefixed by token:
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_match
note: the lint level is defined here
  --> compiler-core/src/lib.rs:2:5
   |
2  |     clippy::all,
   |     ^^^^^^^^^^^
   = note: `#[warn(clippy::collapsible_match)]` implied by `#[warn(clippy::all)]`

Notice this part: with this pattern, prefixed by token:. I was like: is there's something missing in the error message? What kind of token should I prefix it with?

And then I realized that it was really: "with this pattern, prefixed by token:" and it is just a name of the field.

So, I propose to change this and use backticks for separating code from text. Like some other places do:

• "note: #[warn(clippy::collapsible_match)] implied by #[warn(clippy::all)]"
• "warning: this if let can be collapsed into the outer if let"

I have a PR ready!

Version

rustc 1.80.1 (3f5fd8dd4 2024-08-06)
binary: rustc
commit-hash: 3f5fd8dd41153bc5fdca9427e9e05be2c767ba23
commit-date: 2024-08-06
host: aarch64-apple-darwin
release: 1.80.1
LLVM version: 18.1.7

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