Add `state` field to `DepartmentForm`

[michplunkett]

Fixes issue

https://github.com/lucyparsons/OpenOversight/issues/797

Description of Changes

Added state abbreviation dropdown to the department creation and editing page.

Screenshots (if appropriate)

Create Department:

Edit Department:

Show state if it exists for department on list screen:

Show state if it exists for department on download screen:

Tests and linting

• [x] This branch is up-to-date with the develop branch.
• [x] pytest passes on my local development environment.
• [x] pre-commit passes on my local development environment.

[michplunkett]

I will be adding a line and test to require a state value tomorrow morning for both add and edit, but the rest of code should be 💯 . Let me know what y'all think.