Create separate On/Off string resources for Vibration & haptics

Some translators need to be able to adapt the text for On/Off preference
state to match the preference title "Vibration & haptics", which
requires a different inflection and plural form on some languages.

This change separates this resource string from the more generic one
that was used before to allow this flexible translation.

Fix: 228342641
Fix: 229060423
Test: VibrationPreferenceControllerTest
Change-Id: Ib46b3e0d0a980ff57e91f55c73348c440327bad7