Add matching descriptors to scantxoutset output + tests

Summary: This is a patial backport of Core PR14477 : https://github.com/bitcoin/bitcoin/pull/14477/commits/b65326b562cde20aab709a953e396997a6cacbd6

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Differential Revision: https://reviews.bitcoinabc.org/D6138