Bootstrapping EnactState

To form an EnactState, some governance action IDs need to be provided. However, at the time of the initial hard fork into Conway there are no such previous actions. There are effectively two ways to solve this issue:

• populate those fields with IDs chosen in some manner (e.g. random, all zeros, etc.), or

• add a special value to the types to indicate this situation.

In the Haskell implementation the latter solution was chosen. This means that everything that deals with GovActionID needs to be aware of this special case and handle it properly.

This specification could have mirrored this choice, but it is not necessary here: since it is already necessary to assume the absence of hash-collisions (specifically first pre-image resistance) for various properties, we could pick arbitrary initial values to mirror this situation. Then, since GovActionID contains a hash, that arbitrary initial value behaves just like a special case.