This includes a threshold signature in each batch that can be used as a
pseudorandom value.
Also moves `EncryptionSchedule` from `threshold_decrypt` to
`honey_badger`.
* spam protection part 1: remote epoch tracking in HoneyBadger
* moved handling of EpochStarted out of EpochState
* allowed EpochStarted from observers
* removed an unnecessary function call
* updated formatting to beta
* removed an unnecessary variable