phase_area Workflow optimization

**Is your feature request related to a problem? Please describe.**
When implementing new phases the typical workflow would be to assign area/zoneids to phaseids, not vice versa. What do i mean with this:
When picking phase_area option in WDE you are supposed to enter area initially and afterwards have the list of all phases in that area. Phases mostly have 1-5 areas to be assigned to and i don't care about the other phases in these areas while implementing a new phase.

**Describe the solution you'd like**
Initially select phaseid and then get a list of the areas where the phase is already active. So pretty much just swapping phaseid and areaid selection:

Start at the WDE phase_area option and reproduce the current area-first workflow described in the issue. Trace how phase IDs and area IDs are selected, then verify that selecting a phase first shows the areas where it is active and that the existing phase-area assignment workflow still works.

Written by the indexing model from the issue text.