v2 predefined results formats

[NRHelmi]

Adding v2 predefined results formats:

• getTransactions returns TransactionsAsyncMultipleResponses.
• getTransaction returns TransactionAsyncSingleResponse.
• getTransactionResults returns List<ArrowRelation>.
• getTransactionMetadata returns List<TransactionAsyncMetadataResponse>.
• getTransactionProblems returns List<ClientProblem|IntegrityConstraintViolation>.
• executeAsync returns TransactionAsyncResult.