This is mostly just for text type messages at the moment but give the framework so that when other message types can be sent in threads they can be added easily
Create Message attached property to propagate parameters like room, timeline, index and maxContentWidth down to the message content avoiding lots of boilerplate
Move the storage of MessageContentModels to the room in the same manner as memeber objects to prevent duplication but mainly to make the system easier to maintain going forward with things like threads for example. This requires the creation of a MessageContentFilterModel as the same model may be used in multiple places, sometimes with the author showning sometimes not.
It doesn't make sense for a thread to be on the right or tinted when the local user started it as they contain messages from multiple users. So always make them align left and never tint them.
Rework ActionsHandler as static helper functions.
The functions are now invoked from ChatBarCache so there is no need to pass an actions handler object around qml simplifying the code.
So at the moment this remains behind the feature flag as this only adds a threadmodel and a basic visualisation. There is much more to come to get it ready for full release.
Depends on https://github.com/quotient-im/libQuotient/pull/695
Currently basic just to show a working implementation using RoomMember. Currently only the room event and search models are moved over. Will change everything else over once the dependent pr is complete.
