Transaction receipts all in one batch call

[bertllll]

Before you pick this card, make sure you understand the requirements imposed by #782!

At the moment, the BlockchainBridge processes requests of transaction receipts in iterations, repeating contacting the blockchain service as many times as how many pending transactions have been found on the Accountant's side.

Making requests like that is inefficient and the blockchain service provider can punish us with a limit to it. We should implement the batch system, implemented at other places already, also here in order to get better performance, and maybe avoid hitting rate limits if it matters.

Suggestion: some inspiration about implementing the batch request can be seen in the paying mechanism for payables.

Note: this will greatly reduce the API rate overheads of the endpoint use