Add `accountBalanceIntervals` field to `TxBody`

[lehins]

This is the CDDL from the CIP that describes the intervals. We need a new field and lenses in Dijkstra for accountBalanceIntervalsTxBodyL

account_balance_intervals = 
  { + reward_account => 
        [ inclusive_lower_bound: coin, exclusive_upper_bound: coin / null ]  /
        [ inclusive_lower_bound: coin / null, exclusive_upper_bound: coin ] 
  }

transaction_body = 
  {   0  : set<transaction_input>         
  ,   1  : [* transaction_output]      
  ...
  , ? 23 : direct_deposits ; new field
  , ? 24 : account_balance_intervals ; new field
  }