Feature request: RPC for serialization/deserialization

[mvadari]

Motivation

For people developing tools and libraries that serialize/deserialize rippled transactions and objects, there is a lot of difficulty with ensuring that rippled and tooling are aligned, and tooling has been implemented properly to match rippled.

Solution

Create a new RPC (or two, depending on the structure) for handling serialization/deserialization between JSON and rippled-encoded blobs.

This can be an admin-only or standalone-only method, if we want to avoid concerns of having this be a DoS vector for public servers.

There should also be a lot of room for code reuse with the existing sign/submit RPC methods.

Paths Not Taken

You can currently approximate this by signing/submitting a transaction on a standalone/admin node and taking a look at the tx blob returned, but there are some additional complications there (such as you have to construct a whole transaction to do this check, which is tricky if e.g. the field you're checking isn't in any transactions).

[godexsoft]

Examples of binary<->json: https://github.com/XRPLF/xrpl.js/blob/main/packages%2Fripple-binary-codec%2Ftest%2Ffixtures%2Fcodec-fixtures.json

The RPC(s) need to be in xrpld because we need this to work for in-progress STypes.
They should also be admin-only or even standalone-only.