Rollup merge of #104193 - TaKO8Ki:fix-104142, r=cjgillot

Shift no characters when using raw string literals

Fixes #104142

Given the following code:

```rust
fn main() {
    println!(r#"\'\'\'\'\'\'\'\'\'\'\'\'\'\'}"#);
}
```

The current output is:

```
error: invalid format string: unmatched `}` found
 --> src/main.rs:2:59
  |
2 |     println!(r#"\'\'\'\'\'\'\'\'\'\'\'\'\'\'}"#); //~ ERROR invalid format string: unmatched `}` found
  |                                                           ^ unmatched `}` in format string
  |
  = note: if you intended to print `}`, you can escape it using `}}`

error: could not compile `debug_playground` due to previous error
```

The output should look like:

```
error: invalid format string: unmatched `}` found
 --> src/main.rs:2:45
  |
2 |     println!(r#"\'\'\'\'\'\'\'\'\'\'\'\'\'\'}"#); //~ ERROR invalid format string: unmatched `}` found
  |                                             ^ unmatched `}` in format string
  |
  = note: if you intended to print `}`, you can escape it using `}}`

error: could not compile `debug_playground` due to previous error
```

This pull request fixes the wrong span for `invalid format string` error and also solves the ICE.