Provide week-end days data

[tcitworld]

We should provide a method to get the week-end / non-working days for a specific locale.

There seem to be no existing package with such data.

See nextcloud/calendar#2016 (comment)

[ChristophWurst]

How would it work? You just get an array of ints that represent the day of the week?

[tcitworld]

See https://github.com/nextcloud/calendar/pull/2016/files#diff-6e0fb32c14b694cbc2beeb9323557b06R23-R38

[ChristophWurst]

Let's do this :)

[susnux]

Is this still something we want?

[ShGKme]

Is it still actual?