Add a reference script size query

[dnadales]

While integrating the latest version of cardano-ledger to cardano-api, to release node-8.10 I encountered that function estimateMinFeeTx now has a new parameter, which is the total size in bytes of the reference scripts. This function is used in cardano-api here.

We need a query that allows us to calculate the total size in bytes of reference scripts. Based on how this is done in the ledger it seems this query will take only transaction inputs, and output the reference script size by looking up the reference scrips those input transactions point to in the whole UTXO set.

[dnadales]

Superseded by IntersectMBO/cardano-cli#667