[UI] Quick Search Box

[robo-w]

Similar to #29:

Add a quick search box to the navigation bar. If text is entered, the units and incidents shall be searched. If there is a hit in the unit name or one of the address fields of an active incident, the results shall be higher ranked, than in other fields (info, caller, callsign). A patient shall be also searchable by this box.

The result list shall be limited to a small result box, e.g. 5 results.

With the keyboard shortcut "." the focus shall move to the quick search box.