Remove the Dashboard feature that lets an operator send a policy instance to the Admission Control xApp via the A1 mediator.

In the first release, the AC xApp could receive policy (configuration) changes from the dashboard.  In the second release, all A1 policy type and instance communication is performed by the NONRTRIC policy control panel, maintained by Ericss///on.

Stop using the A1 endpoints and remove related UI features.

This is a bit of backfill – no Jira issue was created when the work was done in March 2020.