[Admin app] Add ability to set meetings with other options like every x weeks, or days

Currently an Admin can only set meetings for a day of the week and a time. This is applied for every week in a month but in some cases, the meetings should happen every X weeks, or days.
Having more flexibility here will be better.

Start by locating the Admin app's meeting-scheduling entry point and the existing weekly day-and-time behavior. Clarify which recurrence options are required, including every X weeks and every X days, then define completion as admins being able to configure and save those schedules correctly.

Written by the indexing model from the issue text.