addpsbtoutput: New onchain command for PSBT output and splice_out tests

[ddustin]

Note: This now depends on PR #6677

New addpsbtoutput command for creating a PSBT that can receive funds to the on-chain wallet.

[ddustin]

You need to write a separate set of tests for recvpsbt (is that a good name? addpsbtoutput?). It must test the case where we create, and simply enhance, a PSBT.

I'm leaning toward newoutput to stay in theme with the existing newaddr. How does that sound?

Updated this PR with newoutput and other fixes -- it should be ready to go once when it passes CI.

[rustyrussell]

Just bikeshedding the name now...

[rustyrussell]

Really needs a psbt in here somewhere!

psbtaddoutput?

[rustyrussell]

Also, commit name is now wrong!

[ddustin]

Whoops I read that as addpsbtoutput and changed the name to that 🤦. I kinda like it though -- what do you think?

[rustyrussell]

Looks like you returned success when you meant to return an error:

FAILED tests/test_splicing.py::test_invalid_splice - jsonschema.exceptions.ValidationError: Additional properties are not allowed ('error', 'message' were unexpected)

Failed validating 'additionalProperties' in schema:
    {'$schema': 'http://json-schema.org/draft-07/schema#',
     'added': 'v23.08',
     'additionalProperties': False,
     'properties': {'commitments_secured': {'description': 'whether or not '
                                                           'the '
                                                           'commitments '
                                                           'were secured',
                                            'type': 'boolean'},
                    'psbt': {'description': 'the (incomplete) PSBT of the '
                                            'splice transaction',
                             'type': 'string'}},
     'required': ['psbt', 'commitments_secured'],
     'type': 'object'}

On instance:
    {'error': 'You provided 1000000000msat but committed to '
              '1100000000msat.',
     'message': 'Splice funding too low'}

[ddustin]

Looks like you returned success when you meant to return an error:

FAILED tests/test_splicing.py::test_invalid_splice - jsonschema.exceptions.ValidationError: Additional properties are not allowed ('error', 'message' were unexpected)

Failed validating 'additionalProperties' in schema:
    {'$schema': 'http://json-schema.org/draft-07/schema#',
     'added': 'v23.08',
     'additionalProperties': False,
     'properties': {'commitments_secured': {'description': 'whether or not '
                                                           'the '
                                                           'commitments '
                                                           'were secured',
                                            'type': 'boolean'},
                    'psbt': {'description': 'the (incomplete) PSBT of the '
                                            'splice transaction',
                             'type': 'string'}},
     'required': ['psbt', 'commitments_secured'],
     'type': 'object'}

On instance:
    {'error': 'You provided 1000000000msat but committed to '
              '1100000000msat.',
     'message': 'Splice funding too low'}

Whoops, should be fixed now

[rustyrussell]

One v. minor change: the version number it was added in...

[rustyrussell]

Trivial rebase on master for CI...

Ack 10e1224

[vincenzopalazzo]

Suggested change

	}
	else if(locktime) {
	} else if (locktime) {

FYI just a minor nit

[vincenzopalazzo]

ACK f1dfec4