Core/SystemUI: Update resources

* Remove several aapt warnings
* Remove unused strings
* Move symbol picker strings to cm_extra as they are not meant to be translated, only meant to be adjusted per country. Also removed the strings from all languages, since they were the same.

Change-Id: I2391bdd70a81cd4c126af80b6d9bc7458ea4a639
git merge remote

Change-Id: Iefefa221af1356f1b0a70b1c5156123685c2a239