Support passing transaction as a dictionary in RPC method submit_transaction

RPC method [`submit_transaction`](https://kaspanet.github.io/kaspa-python-sdk/dev/reference/Classes/RpcClient/?h=rpccl#kaspa.RpcClient.submit_transaction) currently supports `transaction` as a [`Transaction`](https://kaspanet.github.io/kaspa-python-sdk/dev/reference/Classes/Transaction/?h=transaction+%28class) instance. This should support passing transaction as a (compatible) dictionary.