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
diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 947e635..969765f 100644
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -247,6 +247,9 @@
     <dimen name="snackbar_min_text_size">12sp</dimen>
     <dimen name="snackbar_max_text_size">14sp</dimen>
 
+<!-- Developer Options -->
+    <dimen name="developer_options_filter_margins">10dp</dimen>
+
 <!-- Theming related -->
     <dimen name="default_dialog_corner_radius">8dp</dimen>