When receiving a message with save a contact in the database in order to
avoid re-calculating image/profile.
This contact is then passed to the client, which can negatively impact
performance.
This commit changes the behavior so that only those contacts that have
some custom fields (have been explicitly added by the user, have been
blocked by the user, have sent a contact request or have a verified ens
name) are passed to the client.
This commit pegs the clock value to maximum + 120 seconds from the whisper
timestamp.
In this way the we avoid the scenario where a client makes the timestamp
increase arbitrarely.
