Move code for processing our own receipts to Room (#4109)
* Move code for processing our own receipts to Room
This is some code to process our own receipts and recalculate our
notification counts.
There was no reason for this to be in client. Room is still rather
large, but at least it makes somewhat more sense there.
Moving as a refactor before I start work on it.
* Add test for the client-side e2e notifications code
* simplify object literal
