readlink: Set silent mode as default

[denendaden]

This primarily changes readlink to be silent rather than verbose by default, in accordance with GNU readlink. It also makes a couple more minor changes, to bring behavior in line with GNU:

• -s, -v, and -q can now be duplicated, and the last one takes priority
• when POSIXLY_CORRECT is set, -s and -q are ignored entirely and it is always verbose (I am not sure if this is intentional behavior on GNU's part but it is how it currently seems to work)

Fixes #10578

[sylvestre]

please add a test to make sure we don't regress in the future, thanks

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/tail/inotify-dir-recreate (passes in this run but fails in the 'main' branch)

[ChrisDryden]

Seems like the windows tests are failing because its expecting the platform specific error message:

.stderr_contains("Invalid argument")

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/factor/t30. tests/factor/t30 is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/factor/t31. tests/factor/t31 is passing on 'main'. Maybe you have to rebase?
Skipping an intermittent issue tests/misc/usage_vs_getopt (passes in this run but fails in the 'main' branch)

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/tail/inotify-dir-recreate (fails in this run but passes in the 'main' branch)

[denendaden]

Hopefully I've taken care of everything. Thanks for the assistance :)

[github-actions]

GNU testsuite comparison:

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

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/mv/mv-special-1. tests/mv/mv-special-1 is passing on 'main'. Maybe you have to rebase?
Congrats! The gnu test tests/pr/bounded-memory is no longer failing!

[ChrisDryden]

Just waiting on the CI