This patch integrates the new a-c BackgroundSyncManager, which is the
main entry point for interacting with Sync. Behind the scenes, it uses
WorkManager in order to sync configured syncable stores.
Current behaviour:
- sync runs on start, with a slight delay
- sync runs on a schedule few times a day, to lessen the startup sync burden
Also included is a basic UI integration in order to allow user to synchronize
on demand, and monitor sync state.
This patch integrates relevant a-c components, and updates the current Preferences
UI to allow signing-in and displaying basic account information (email, displayName).
Currently there's no Accounts UI, and so singing out or otherwise interacting with the
account isn't possible.
Grisha Kruglov