Feature/message state

[cejanen]

First version of message states. Few notes below.

• To keep it simple message state was added to message representing also for set, it seems to be nicer that having mutating function. Message has to be replaced in payload anyway
• There is still one TODO. Need to set failure state only for network error
• If possible code was documented
• ChatCore was a bit cleaned up. On top are public extensions & methods. Underneath are private & helper methods. To handle tempMessage flow private enum is used in its extension scope.
• When message representing implementation was changed I also unified usage of self in inits. Although I prefer to have self only in places its necessary.
• To avoid multiple listeners updates in short time (it was possible to see both temp message & stored message for while) I created listener throttler which works in instant time when adding / removing temp messsage. For network listener callback if temp message is in messages it waits some time to be cancelled and recalled with correctly removed message.
• Temp message needs ID which is taken from cached message (only relation they have but can be identified if needed)
• IDEA: ChatCore is growing fast. We should figure out how to split it to keep good maintenance.

[cejanen]

I added a few comments, plus, weird things are happening to me. You can find recording here: https://drive.google.com/file/d/1t05iiFu4UWyp0ZCUMigULJo0thf_R7Yv/view?usp=sharing

I cant play that video. Then Ill look at it :-D

[cejanen]

@schwarja I updated discussed topics. About video and srolling. I checked that data are sorted right way. I also created new task to enhance data managers or whole behavior when new message appears. ALso when new message from the other side you lost latest message and load more messages button is not managed correctly.