lineage-sdk: Use PreferenceDataStore for lineage-sdk preferences

Replaces the need for:
https://github.com/LineageOS/android_frameworks_support/commit/32e67e60201feee32b5af8ef4bb66c98292cd3b7

*) frameworks/support are now built with gradle and are included as prebuilts.

*) API level 26 (8.0) introduced PreferenceDataStorage which can be used
   to implement what we need without touching the support library.

Change-Id: Ide3417019ccf8bde5dca3b2aec3d2075e7c8b597