Add data_set column for raw contacts and groups.

This provides a way for multiple sync adapters to exist for a single
account type.  Internally, for example, we can use these new columns
to support separate sync adapters (and sourced data) for Focus,
Emerald Sea, and Latitude.

Change-Id: I1b8dfd79e9fb2dfcee6ac6d4adb947093f5c2324