Fixes a bug where, if multiple Matrix users had used the same reaction on a message, and then one of those Matrix users removed their reactions, the bot would forcibly remove all of that reactions. Now, we check and make sure there are no remaining reactions from Matrix before removal.
This also rewrote the retrigger system to be more generic and to use promises instead of re-entry (would lose call stack).
Co-authored-by: Cadence Ember <cadence@disroot.org>
Reviewed-on: https://gitdab.com/cadence/out-of-your-element/pulls/85