df(windows): real usage and mount points; -a, -l, -t, -x, -T, --total, --output, -i and PATH operands now work

[nikolalukovic]

No description provided.

[codspeed-hq]

Merging this PR will not alter performance

✅ 367 untouched benchmarks
⏩ 50 skipped benchmarks¹

---

_{Comparing nikolalukovic:df-windows-fix (69a1b0f) with main (65b5ca4)²}

Footnotes

1. 50 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. ↩

2. No successful run was found on main (6f65091) during the generation of this report, so 65b5ca4 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/misc/tty-eof (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/rm/isatty (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/tail/symlink (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/tail/tail-n0f (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/date/date-locale-hour (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/date/resolution (passes in this run but fails in the 'main' branch)
Note: The gnu test tests/expand/bounded-memory is now being skipped but was previously passing.
Congrats! The gnu test tests/printf/printf-surprise is now passing!

[nikolalukovic]

merging #12244 before this one would be a good idea imo @sylvestre @lhecker

EDIT: actually after #14455 got merged I guess it doesn't matter any more, there will be lots of conflicts either way