Add ability to combine multiple Chats

Multiple chat Backups should be combinable (from the same person's phone).
The data must be merged. I propose the following equality constraints for messages:

- The player's name matches
- AND the Wordle index matches
- AND the number of streaks matches (<- this could make problems when you are on a 0 streak in Wördle)

Then there should be no Merge problems except when the messages were tempered with in which case either the newest or oldest message with a certain `(player, wordleIdx, streak)` combination should be parsed and passed on.