Highlight search string match.

Change-Id: I72c0380512028674c91f287325f221a686a4821d
Improve search performance.

The normalization regex is slow (5-10ms per entry on mako), so better
pre-cache it. Also cache the icons, as the number of icons is vastly
smaller than the number of potential search results, so they'll be
reused very often.

The regex change alone brings the duration of a single filter run down
to ~20ms from ~1200ms on mako.

Change-Id: Ia0fa9c554d0d585a52c8a2b87eecbf045388c961
Settings: Bump SettingsSearch db version.

Change-Id: I0ba3be71f61fcae9c2fe67064b5f890fdd0abb2c