Give a descriptor from createmultisig and addmultisigaddress.
Extracted from #16528 with addmultisgaddress and tests added.
Code review ACK, briefly tested.
Why didn't we think of this earlier?
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The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.
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No conflicts as of last run.
Also add a mention to doc/descriptors.md?
Added a mention in descriptors.md
tACK 19a354b11f85a3c6c81ff83bf702bf7a40cf5046
Code review ACK 19a354b11f85a3c6c81ff83bf702bf7a40cf5046.
utACK 19a354b11f85a3c6c81ff83bf702bf7a40cf5046
ACK 19a354b11f85a3c6c81ff83bf702bf7a40cf5046