It is best to store all key origin information
(master key fingerprint and all derivation steps)
in the multisig descriptor. Being explicit with
this information should be beneficial if this approach
is used with other wallets/signers (whether hardware
or software). There is no harm including all of this
with xpubs (if anything it simplifies the test code)
and makes this example/docs more complete and safer
incase it is referenced by others.
Review note: The changes are complete, because self.options.descriptors
is set to None in parse_args (test_framework.py).
A value of None implies -disablewallet, see the previous commit.
So if a call to add_wallet_options is missing, it will lead to a test
failure when the wallet is compiled in.
wallet_multisig_descriptor_psbt.py is refactored in this commit. While
behavior doesn't change we do cleanup the way wallets are accessed
throughout the test as this is done a lot for the various signers
and their multisigs. We also get rid of some shallow methods and
instead inline them for improved readability.
descriptors.md is improved to be more explicit about which wallet
(ie the signer or multisig) is required for each step.
