Ability to restore old versions of follow lists (kind 3)

[aaccioly]

It would be nice if Haven kept a few backups of older versions of the owner's follow list (Kind 3) and provided an easy command to restore them.

Suggested implementation:

Every time Haven receives a new Kind 3 for the relay owner's pubkey, it should check if it’s a new version and store a copy.

Haven should keep:

• The 10 latest versions of the Kind 3
• The most recent Kind 3 from each of the last 4 weeks
• The most recent Kind 3 from each of the last 12 months
• The most recent Kind 3 from every year, for up to 10 years

All of these settings could be configurable.

Haven should also provide commands to:

• List previous Kind 3 versions with dates and number of followers
• Select and display one of the available versions
  *Restore a previous follow list (i.e., publish a new Kind 3 with the same tags as the selected backup version)

This feature is heavily inspired by Citrine and https://nostr.land/restore that saved me many, many times when clients corrupt my kind 3.