[CSL-680] Define 'instance Enum EpochOrSlot'
[CSL-680] Define 'instance Enum EpochOrSlot'

input-output-hk/cardano-sl,input-output-hk/pos-haskell-prototype,input-output-hk/pos-haskell-prototype,input-output-hk/cardano-sl,input-output-hk/cardano-sl,input-output-hk/pos-haskell-prototype,input-output-hk/cardano-sl