Consolidate enum labels and default values for front-end

[carrythebanner]

The front-end was defining enum values & labels in multiple places (e.g. area 'P' = 'Portland'). This consolidates those in one place, and separates the UI-building logic from the specific values.

[carrythebanner]

This also encapsulates the code building the time options into its own function.

Eventually we may want to replace the drop-down menu of times with a basic <input type="time">, but I ran into a couple of issues when I attempted. For now, this just streamlines populateEditForm() by encapsulating the existing time logic.