[api] add rel filter on emerald/transactions

[Andrew7234]

No description provided.

[mitjat]

Thank you! LGTM provided you tested e2e locally.

[Andrew7234]

tested e2e locally.

Yep tested locally and confirmed that the returned transactions are associated with the rel address. It should be noted that for evm.Call transactions, the rel address often only appears in the events associated with that transaction and is not displayed within the transaction itself (eg as sender or to). This can be checked by querying emerald/events?tx_hash={some_tx_hash} and inspecting the returned events for the rel address