Enhance TestCase::assertLocalizedHolidays

[KJhellico]

TestCase::assertLocalizedHolidays now considers all categories of holidays, but doesn't consider subdivisions holidays. However, in Switzerland, for example, there are only a few national holidays, and the test looks like this:

    def test_l10n_en_us(self):
        self.assertLocalizedHolidays(
            "en_US",
            ("2023-01-01", "New Year's Day"),
            ("2023-05-18", "Ascension Day"),
            ("2023-08-01", "National Day"),
            ("2023-12-25", "Christmas Day"),
        )

If we include provincial holidays, the test will look like this:

    def test_l10n_en_us(self):
        self.assertLocalizedHolidays(
            "en_US",
            ("2023-01-01", "New Year's Day"),
            ("2023-01-02", "Berchtold's Day"),
            ("2023-01-06", "Epiphany"),
            ("2023-03-01", "Republic Day"),
            ("2023-03-19", "Saint Joseph's Day"),
            ("2023-04-07", "Good Friday"),
            ("2023-04-10", "Easter Monday"),
            ("2023-04-13", "Battle of Naefels Victory Day"),
            ("2023-05-01", "Labor Day"),
            ("2023-05-18", "Ascension Day"),
            ("2023-05-29", "Whit Monday"),
            ("2023-06-08", "Corpus Christi"),
            ("2023-06-23", "Independence Day"),
            ("2023-06-29", "Saints Peter and Paul"),
            ("2023-08-01", "National Day"),
            ("2023-08-15", "Assumption Day"),
            ("2023-09-07", "Genevan Fast"),
            ("2023-09-18", "Prayer Monday"),
            ("2023-09-25", "Saint Nicholas of Flüe"),
            ("2023-11-01", "All Saints' Day"),
            ("2023-12-08", "Immaculate Conception"),
            ("2023-12-25", "Christmas Day"),
            ("2023-12-26", "Saint Stephen's Day"),
            ("2023-12-31", "Restoration Day"),
        )

Should we do this or is it an impractical overkill?

[arkid15r]

Yes, it'd be great to have subdivs covered as well. I didn't look into the implementation details yet.
@KJhellico do you want to work on the implementation?

[KJhellico]

Yes, I am already on it. 😋