API needs an endpoint to submit a package of txs

[stevenroose]

Currently there is the POST /tx endpoint where you can submit a tx. With Bitcoin Core 28 releasing package relay in a limited form, it is possible using Core to submit and relay packages of transactions. More specifically, it is possible to relay a pair of txs of which either of them would not be accepted into the mempool alone.

This means that submitting the txs one by one into the /tx endpoint does not work and the API needs to be able to accept packages of multiple (currently just 2) transactions.

Maybe POST /tx can support a body of multiple lines, or of a JSON array, or a new endpoint /txs can be added.