Improve folder sync.

- On initial sync, make sure that all required folders exist.
- Enable sync for all syncable folder types.
- Do not try to sync local-only folders.

Some bugs exposed by this change:
- Drafts synced from server are non-editable.
- Deleting from trash is weird.

Bug: 9987081
Bug: 9842867

Change-Id: Iddf1b16ee3977e89545ead3165a5847fdf90cefc
3 files changed