mv: show file mode in interactive prompt for read-only targets

[skjha98]

Description
Fixes the GNU compatibility gap where mv -i fails to show the octal mode and permission string when prompting to overwrite a read-only file (GNU test i-3).

Key Changes

• Logic: Added Unix permission check to mv.rs to detect files lacking owner-write bits.
• Format: Used a invisible character (\u{200c}) in the octal string to prevent Fluent from stripping the leading zero (e.g., ensuring 0444 doesn't display as 444).
• L10n: Added mv-prompt-overriding-mode to en-US and fr-FR locales.

Verification

• Manual Verification:
  • Before: mv: overwrite 'dest'?
  • After: mv: overwrite 'dest', overriding mode 0400 (r--------)?
• Compliance: clippy and fmt are clean.

[github-actions]

GNU testsuite comparison:

Note: The gnu test tests/pr/pr-tests was skipped on 'main' but is now failing.

[ChrisDryden]

I have a similar pr for this, going to compare the two today later because I'm sure I've missed something #9599

[skjha98]

Thanks, @ChrisDryden I'm quite new to Rust and this is my second contribution to uutils (and open source in general), so I'm happy to learn from the comparison.

I put this together to address the GNU i-3 failure specifically. I also noticed that the Fluent engine strips leading zeros from octal numbers, so I used a invisible character(\u{200c}) as a workaround to keep it as 0444 instead of 444.

Looking forward to your thoughts!

[github-actions]

GNU testsuite comparison:

Note: The gnu test tests/printf/printf-surprise is now being skipped but was previously passing.

[sylvestre]

Could you please fix the conflicts? Thanks

[skjha98]

I see that i-3 is now passing on the main coverage page thanks to @ChrisDryden PR. Since the issue is resolved, I'll close this PR. It was a great learning experience for my first contribution to uutils—thanks everyone!