Rework of message state to resolve a circular dependency between

ChatMessagePrivate::setParticipantState and
ChatMessagePrivate::setState.

All event regarding a chat message will now chat the state of a
participant and then if neecesary the state of the chat message will
follow.

For IMDN controlled stats (i.e. DeliveredToUser, NotDelivered and
Displayed), the state of the chat message will be deduced based on the
states of all participants

For non-IMDN controlled states, the state of the chat message will
follow the state of the me of the chat room the message it associated
with