This updates the UI to use the new fuzzy search API. It’s a drop-in
replacement so the / shortcut to jump to search is preserved, and
results can be cycled through and chosen via arrow keys and the
enter key.

It doesn’t use everything returned by the API:
* deployments and evaluations: these match by id, doesn’t seem like
  people would know those or benefit from quick navigation to them
* namespaces: doesn’t seem useful as they currently function
* scaling policies
* tasks: the response doesn’t include an allocation id, which means they
  can’t be navigated to in the UI without an additional query
* CSI volumes: aren’t actually returned by the API

Since there’s no API to check the server configuration and know whether
the feature has been disabled, this adds another query in
route:application#beforeModel that acts as feature detection: if the
attempt to query fails (500), the global search field is hidden.

Upo...