Cardano Updates

Signed-off-by: cryptodj413 <[email protected]>

Remove inline Cardano.Read.Ledger.* and Block.Gen modules,
consume from cardano-ledger-read node-10.6.2 branch instead.
Mirrors the same refactoring done on master (PRs #5204, #5206).

That filed can be removed, since it was only used to filter out
stake pools that didn't have delegators for the purpose of
calculation of `PoolDistr` and in the ledger state `GetStakeSnapshots`
query. The reason why we can remove this field and preserve previous
behavior is because stake pool will not have any delegations iff such
pool also doesn't have any stake associated with it. That is because
delegations with zero stake are filtered out as part of
`resolveInstantStake` computation.

Record CON-58 invoice consensus payment

Update Gen modules to use EraBlockBody (mkBasicBlockBody, txSeqBlockBodyL)
instead of EraSegWits (toTxSeq), add DijkstraEra to HeaderEra type family,
and add Dijkstra test coverage (block + tx tests).