make all invite notifications ephemeral (?)

STUB

value

• to make invitations less confusing, we want to share the full phone number of invitees to their inviters in both command responses and acceptance notifications
• however, we introduce some (very small!) chance of increased likelihood of leaking invitee phone numbers this way [1]
• to avoid this, consider making all invite notifications disappear after some interval (say 30 minutes?) by (1) setting the disappearing message timer to that interval, (2) sending the notification, (3) setting the disappearing message timer back to whatever it was before

[1] only scenario in which this happens:

1. disappearing messages are on when alice invites lola
2. disappearing messages are turned off
3. lola accepts

result: the phone number contained in the invite message itself disappears, while the acceptance notification does not. (note: in all other scenarios, sending the full number in the acceptance notification does not decrease chances of leak, because the number was already contained in the invite message itself, which therefore dominates the consideration of likelihood of data leak.)

behavior

TK-TODO

implementation

• use signal.setExpiry to change timer
• consult channel.messageExpirtyTime to set it back to original value