[On-device backup] backup feature improvements

[86doteth]

Description

1. have untrusted marks of users backed up
2. have cr messages of pending contact requests backed up. its empty now and only shows on original profile, but when accepting from original profile and both instances are paired then the request message does show up in the chat on both instances. havent tested what happens when accepting on the new instance first or without pairing
3. have emoji reactions backed up as well (think i saw an issue for it somewhere but just collecting everything backup-related my heart desires here for now)
4. have spectated communities backed up as well, or at least give the option to (some communities i dont really want to signal to be a part of but do want to observe since theyre public)

also just a heads-up in case its forgotten in a stale issue somewhere: rejecting contact requests isnt synced among instances, paired or unpaired. it does sync for accepts tho, would be nice to tidy this up, had to manually do this for both old and new instance (in case i want to use the old one still)

[sunleos]

@86doteth,

also just a heads-up in case its forgotten in a stale issue somewhere: rejecting contact requests isnt synced among instances, paired or unpaired. it does sync for accepts tho, would be nice to tidy this up, had to manually do this for both old and new instance (in case i want to use the old one still)

moved this improvement to a separate ticket since I could not find the original one: #19587