Clear out orphaned messages in updates/deletes tables

Case #1:
* Fixes #2184702
* Messages can be in the base Messages table, but also in
  Message_Deletes and Message_Updates; the latter two were not
  being purged of deleted messages.
* This CL deletes from all three tables when a Mailbox is deleted
* Also run a check for orphaned deletes/updates when the email
  provider's db is first opened
* Unit test updated to check for proper deletion
* Unit test for the provider check for orphans

Case #2:
* Fixes #2184708
* Messages in Outbox/Drafts can get modified or deleted, but the
  rows added to the updates/delete tables never get removed because
  the boxes don't sync
* Added code to (which gets notifications of these
  changes) to delete these rows

Change-Id: Ib53e441136b0da1e88bc220150d631999058a8f0
1 file changed