Because swarm is a synched history compatible with multi-devices,
if a message from the swarm is read on one device it should be
synchronized with other devices as much as possible.
The idea of this patch is to add lastDisplayed sent in synched
datas to allow clients to update the read status. However, there
is several scenarios to take into account, because the history
can be partially synched across devices.

5 scenarios are supported:
+ if the last displayed sent by other devices is the same as the
current one, there is nothing to do.
+ if there is no last displayed for the current device, the remote
displayed message is used.
+ if the remote last displayed is not present in the repo, it means
that the commit will be fetched later, so cache the result
+ if the remote is already fetched, we check that the local last
displayed is before in the history to replace it
+ Finally if a message is announced from the same author, it means
that we need to update the last displayed.

If the last displayed message is updated, AccountMessageStatusChanged
is triggered for the client.

Doc: https://git.jami.net/savoirfairelinux/jami-project/-/wikis/technical/2.3.%20Swarm
Change-Id: Iedd29129d72cbeb43499471bdfd492dd4d49dcb6