Add setting to change first day of the week: Issue #844 (#910)

<!-- Thank you for submitting a pull request! Make sure to follow the
instructions to write release notes for your PR — it should only take a
minute or two:
https://github.com/actualbudget/docs#writing-good-release-notes -->

Resolves issue #844 .

---------

Co-authored-by: biohzrddd <>