date: Tests for Hungarian locale

[MegaBrutal]

Due to frequent breakage of the Hungarian locale of the date command (#10921, #11240), I want to add some tests. This patch contains:

1. An amendment for the existing month name test to include Hungarian.
2. A new test for the Hungarian date format (basically copied and adapted the French test which is similar).

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/date/date-locale-hour (passes in this run but fails in the 'main' branch)
Note: The gnu test tests/tail/tail-n0f is now being skipped but was previously passing.
Note: The gnu test tests/env/env-signal-handler was skipped on 'main' but is now failing.

[oech3]

Please fix clippy error

[MegaBrutal]

@oech3 Clippy doesn't give me any warnings for the code. However the test itself obviously fails, as it's for the problem reported in #11240.

[oech3]

You cannot add tests until the bug was fixed.
clippy warning are shown at https://github.com/uutils/coreutils/actions/runs/23027922037/job/66911166142?pr=11309

[sylvestre]

Please add the ignore for the test

[MegaBrutal]

I must have fixed the clippy. Why did my clippy not show this problem though?
I can't fix the actual problem, I just want to add this test to prevent breaking again after it's fixed.