Transaction hash confirmation

[adriantpaez]

Now we are storing transactions in the database without confirming the transaction hash, that's not a problem because StarkNet is centralized, but in the future when P2P comes alive we need to verify all the information sent by the other peers of the network. Transaction hash calculation can now be used to confirm the data obtained from the Feeder Gateway during the sync process.

A good starting point might be to implement a util function that receives our transaction type used by the database and returns the hash computation as a Felt

Transaction hash is defined here: https://docs.starknet.io/docs/Blocks/transactions