Support for non-working/rest days

[jbx1]

More information

Weekends are typically considered non-working days. While not public holidays (so shops might still be open), offices are typically closed.
While these are typically Saturday and Sunday in most western countries, they are different in countries such as the middle east and north Africa, Asia and central america, where the "weekend" might be Friday and Saturday, or in some cases only one day.

https://www.hireborderless.com/post/weekend-rest-days-around-the-world

It would be a nice feature to add to this library, to also get rest days, which are not public holidays, since it is useful for certain applications.

Separate discussion about this feature: https://stackoverflow.com/questions/17927854/how-to-check-if-a-certain-date-is-a-weekend-taking-into-account-the-current-loca