Rollup merge of #144609 - Muscraft:right-align, r=compiler-errors

feat: Right align line numbers

As part of my work on getting `annotate-snipptes` to be used as `rustc`'s renderer, I realized that `rustc` left-aligned line numbers, while `annotate-snippets` right-aligned them. This PR switches `rustc` to right-align the line numbers, matching `annotate-snippets`. In practice, this change isn't very noticeable in day-to-day output, as it only shows up when a diagnostic span contains line numbers with different lengths (9->10, 99->100, 999->1000, etc.).

`rustc`
```
error[E0412]: cannot find type `F` in this scope
  --> $DIR/ui-testing-optout.rs:92:10
   |
4  | type A = B;
   | ----------- similarly named type alias `A` defined here
...
92 | type E = F;
   |          ^ help: a type alias with a similar name exists: `A`
```
`annotate-snippets`
```
error[E0412]: cannot find type `F` in this scope
  --> $DIR/ui-testing-optout.rs:92:10
   |
 4 | type A = B;
   | ----------- similarly named type alias `A` defined here
...
92 | type E = F;
   |          ^ help: a type alias with a similar name exists: `A`
```

r? ``@compiler-errors``

0 files changed, 0 insertions, 0 deletions