Rollup merge of #80160 - diondokter:move_async_fix, r=davidtwco

Implemented a compiler diagnostic for move async mistake

Fixes #79694

First time contributing, so I hope I'm doing everything right.
(If not, please correct me!)

This code performs a check when a move capture clause is parsed. The check is to detect if the user has reversed the async move keywords and to provide a diagnostic with a suggestion to fix it.

Checked code:
```rust
fn main() {
    move async { };
}
```

Previous output:
```txt
PS C:\Repos\move_async_test> cargo build
   Compiling move_async_test v0.1.0 (C:\Repos\move_async_test)
error: expected one of `|` or `||`, found keyword `async`
 --> src\main.rs:2:10
  |
2 |     move async { };
  |          ^^^^^ expected one of `|` or `||`

error: aborting due to previous error

error: could not compile `move_async_test`
```

New output:
```txt
PS C:\Repos\move_async_test> cargo +dev build
   Compiling move_async_test v0.1.0 (C:\Repos\move_async_test)
error: the order of `move` and `async` is incorrect
 --> src\main.rs:2:13
  |
2 |     let _ = move async { };
  |             ^^^^^^^^^^
  |
help: try switching the order
  |
2 |     let _ = async move { };
  |             ^^^^^^^^^^

error: aborting due to previous error

error: could not compile `move_async_test`
```

Is there a file/module where these kind of things are tested?
Would love some feedback 😄

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