Submit batch transactions

This allows you to submit multiple transactions. The response has three outcomes:

1. All transactions succeed, and it will return a 202
2. Some transactions succeed, and it will return the failed transactions and a 206
3. No transactions succeed, and it will also return the failed transactions and a 206

To submit a transaction as JSON, you must submit a SubmitTransactionRequest.
To build this request, do the following:

1. Encode the transaction as BCS. If you are using a language that has
   native BCS support, make sure to use that library. If not, you may take
   advantage of /transactions/encode_submission. When using this
   endpoint, make sure you trust the node you're talking to, as it is
   possible they could manipulate your request.
2. Sign the encoded transaction and use it to create a TransactionSignature.
3. Submit the request. Make sure to use the "application/json" Content-Type.

To submit a transaction as BCS, you must submit a SignedTransaction
encoded as BCS. See SignedTransaction in types/src/transaction/mod.rs.
Make sure to use the application/x.aptos.signed_transaction+bcs Content-Type.