Add default cloud provider RRO to be configured by OEMs

Added the ability to set default cloud provider based on RROs set by
OEMs. If there is only one cloud provider, it will be selected as default automatically.

Bug: 196072575
Test: atest PickerSyncControllerTest && Manual
Change-Id: Ie99dd9532905ba65bc7ccc34ed08e6739e200cff
Merged-In: Ie336b8e9baa71dea79eea0db4de0ef00475fdef3
5 files changed