Restore message drafts

[robert-virkus]

Is your feature request related to a problem? Please describe.

• After leaving a chat, a draft text is not restored when re-entering the chat.

Describe the solution you'd like
Message drafts should be restored when re-entering a chat.
This includes the following cases:

• Have a possible draft for each conversation, ie a different draft may be restored for conversation A than for conversation B
• Restore message drafts after restarting the app
• When a conversation is deleted, the corresponding draft also should be deleted
• Question is if binary messages which may potentially be very large, should also be persisted and restored - I do not think that such messages need to be restored, at least not when restarting the app

Describe alternatives you've considered

• Discarding message drafts when leaving a conversation (as it is now), but this provides not a good UX

Additional context
none