tail: Handle missing/dir paths via metadata()

[Xylphy]

Closes #10193

This pull request refactors error handling in the tail_file function in src/uu/tail/src/tail.rs to use path.metadata() for file checks and improves error reporting formatting.

Error handling and logic improvements:

• Changed file existence and directory checks to use path.metadata(), enabling more robust detection of missing files and directories. This replaces separate checks for existence and directory status with a single match statement.
• Added explicit handling for ErrorKind::NotFound to ensure missing files are reported with the correct error message and observer update, then exit early.

Error reporting formatting:

• Updated error message formatting to use multi-line translate! calls for better readability and consistency across permission and file opening errors.

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/fmt/non-space. tests/fmt/non-space is passing on 'main'. Maybe you have to rebase?
Skip an intermittent issue tests/tty/tty-eof (fails in this run but passes in the 'main' branch)

[sylvestre]

please fix the jobs

[codspeed-hq]

Merging this PR will not alter performance

✅ 284 untouched benchmarks
⏩ 38 skipped benchmarks¹

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_{Comparing Xylphy:tail-metadata-error-handling (3d21f21) with main (ec7e81e)}

Footnotes

1. 38 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[Xylphy]

@sylvestre Done!

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/misc/tee (fails in this run but passes in the 'main' branch)

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/basenc/bounded-memory is now passing!

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/pr/bounded-memory is no longer failing!