Create/edit a page: Assigning a department when you belong to multiple

### As an editor or moderator who belongs to multiple departments, I want to be able to select which department the page I'm authoring is for, so that I can attribute content to the right department.

**Is your feature request related to a problem? Please describe.**
Currently, we can assign a user to multiple departments. If that user is not an admin, when they create a page, that page will be associated with all of that user's permission departments, and if department pages are attached to each of those permission departments, then on Janis the pages will appear as "Offered by" all those departments. We might not want that, because someone might just want to

We should work on this when we have moderators/editors that belong to multiple departments, but otherwise deprioritize.

**Describe the solution you'd like**
This could easily be selected in the create content modal, following the "select a department" pattern we have when admins create a page.

**Describe alternatives you've considered**
Maybe adding back the ability to change assigned departments on the edit page? Maybe not.

**Additional context**
Add any other context or screenshots about the feature request here.