[FLIP 204] Update bootstrapping/sporking process

[jordanschalm]

Context

See FLIP 204 for details.

Definition of Done

• Add mechanism to set TargetEndTime in bootstrapping/sporking process
  • Option 1: Add an optional flag to explicitly the desired epoch duration (seconds). We can compute a reference counter/timestamp.
  • Option 2: Compute an initial duration config value, based on the committee size and epoch length and expected view rate.
• Update network instantiation
  • Default value for deploying FlowEpoch
• Enable cruise control by default