Redesign outgoing message database

[andmcadams]

Currently, there is a single database with a single table on the Mac that holds outgoing messages (normal messages and reactions). Due to differing amounts of info required for each of these, it might make sense to split them up into different tables.

Things to keep in mind include:

• Any solution should be extendable to other message types (add/remove from group, rename group, etc)
• Order needs to be maintained to some degree, especially for add/remove from group
• What info is actually required for each message type?

[andmcadams]

This is probably a good time to investigate other message types and figure out exactly what info is needed for them. Message types to examine include:

1. Group renaming
2. Group add/removal of participant
3. Attachments (current test build does not use minimal data)