Feature flags can affect the initial search query when
the app loads. eg. If the groups feature is enabled then
we will by default load annotations for the most recently
used group, otherwise we'll load public annotations.

Therefore, wait for the feature flags to be retrieved
before loading the view.

The feature flags endpoint is very fast so the behavior
was correct most of the time previously but occassionally
the app would load and fetch Public annotations before
the feature data was available which would have resulted
in fetching group annotations.

At the same time, this clears the feature flag data
when the current user changes and fixes an issue where
switching from a non-groups enabled account to a groups-enabled
account did not immediately update the UI.

Fixes #2675