Add filtering of preferences in developer options

Search will recursively go into each preference group and set visibility of preferences based on title match. If a preference group (category) has no preferences, we will hide that preference group as well.

All queries and titles are sanitized by turning them to lower case and replacing underscores with spaces for convenience.

Change-Id: Ibdc689d74d0c872c92c1d523bbc0efdb9e31aecd