admins can undo recycle

Value

• we might accidentally remove a channel that people still want to use, that's jarring!
• would be nice to let people know a channel is going to get deleted and give them a way to undo that!

Behavior

WHEN a maintainer issues a recycle command for a channel

• THEN the admins will receive a notification that says Your channel is about to be deactivated due to lack of use. To continue using the channel, respond with any message in the next 24 hours.
• IF admins respond within 24 hours, THEN their channel will not be recycled
• IF admins do not respond withing 24 hours, THEN their channel will be recycled (and they will receive notification that says Your channel is being deactivated due to lack of use. To create a new channel, visit https://signalboost.info

Implementation details

• recycle command puts a channel into a (new) recycleQueue table
  • fields: channelPhoneNumber (string), whenEnqueued (datetime)
• every hour a job runs that checks the recycle queue checkForRecyclableNumbers (or something)
• it removes from the recycle queue any channels that meet the following criteria:
  • (1) the channels messageCounts entry was last updated less than 24 hours ago
• it recycles any channels that meet the following 2 criteria (and then deletes them from the queue):
  • (1) the the channel's recycleQueue entry was created more than 24 hours ago
  • (2) the channel's messageCounts entry was last updated more than 24 hours ago

additional TODO:

• destroy should also destroy entry in recycleablePhoneNumbers
• refactor registrar#notify to use correct lang prefs/notification

Open Questions

• what about destroy commands? options:
  • (1) impose a delay on destroy commands issued by maintainers (via cli) but not by admins (via signalboost command)?
  • (2) don't impose any delay on destroy commands and also don't expose it via the cli? if maintainers want to destroy a channel they have to first recycle it, then wait a day, then destroy it?