Prevent account flip flopping from compose

There were two issues:
- the default account ID from the provider wasn't consistent: it was
using a snapshot from the cached data but that simply returns a Map, and
the values aren't guaranteed to be sorted (and indeed I saw that the
order was different on consecutive calls!)
- hitting app up from Compose always just kicked you out to the inbox
for the default account, but it probably should have used the account of
the compose screen, since it can be specified in the Intent

Bug: 5012008
Change-Id: Ic9a753b261e047790453bc1a9417bc0c6d2f87f9
3 files changed