Better hook into geocoder search command

Currently there isn't a great way to execute code after `search` is executed on `GeocoderViewModel`.

- `GeocodeViewModel.search` is a command so we can listen to the `afterExecute` event, but this doesn't wait for the geocode promise to complete
- The `GeocodeViewModel.complete` is raised only after the geocode is successful and the camera flight finishes

What do I do when `search` is executed and either the geocode is not executed or the geocode promise fails?

Start by reading the GeocoderViewModel.search command and its complete event, as named in the issue. Trace how unsuccessful searches and rejected geocode promises are handled. Done would mean the issue specifies and implements a reliable hook covering those outcomes, with tests for each case.

Written by the indexing model from the issue text.