Fix \r and \r\n handling in t- and f-string debug texts

[MichaReiser]

Summary

Fixes #18667

The Printer only supports \n. We, therefore, need to normalize the newlines in debug texts during formatting.

Normalizing the newlines doesn't change the Python semantics because Python normalizes all newlines to \n

Test Plan

Added snapshot test

[github-actions]

ruff-ecosystem results

Formatter (stable)

✅ ecosystem check detected no format changes.

Formatter (preview)

✅ ecosystem check detected no format changes.

[ntBre]

Nice! This makes sense to me.

[MichaReiser]

I was a bit confused why this would lead to duplicate lines but I think I understand it now:

1. We infer \r\n as the used line ending because it's the first we see
2. The printer replaces every \n with \r\n which results in \r\r\n after the first formatting pass

Now we have two line breaks. The printer will now infer \r as the line ending, and replace the \n with \r, now we have three line endings. The editor might also decide to convert the \r to \r\n, in which case this goes on forever