"namerawtransaction" equivalent for PSBT API

[JeremyRand]

Is your feature request related to a problem? Please describe.

In the raw transaction API, creating a transaction with a name output is done as follows:

1. Create a transaction with a currency output via createrawtransaction.
2. Add a name operation to that output using namerawtransaction.

Unfortunately, the latter operation does not have any analogue currently in the PSBT API. Thus AFAICT it is not possible to create name transactions via the PSBT API right now.

Describe the solution you'd like

It would be useful to add a namepsbt RPC method that does what namerawtransaction does, but for PSBT's.

Describe alternatives you've considered

I considered adding name information to createpsbt itself, but it makes the syntax rather unwieldy.

Additional context

This is relevant to atomic name trades.

[JeremyRand]

@domob1812 Is this something that Xaya would find relevant?

[domob1812]

Yes, that's definitely something useful for Xaya as well. I can work on this, ETA a week or two maybe (depending a bit on how much time I find and what I need to do for other things).