235550d019 Take non-importing keys into account for spendability warning in descriptor import (Pieter Wuille)
802dcd37d1 Import all origin info in importmulti; even for non-importing pubkeys (Pieter Wuille)
7fcbe7dc11 Keep full pubkeys in FlatSigningProvider::origins (Pieter Wuille)
Pull request description:
Clean backport of #15749 by sipa to 0.18
ACKs for commit 235550:
fanquake:
utACK 235550d
MarcoFalke:
ACK 235550d019 (Checked that they are clean cherry-picks)
Tree-SHA512: 1ccc19f51137ac4ef971c0bcca4c87ab2383610aa51c5d02680c485b9ce6abd698dddd7f4a45946d56b1aa741cc3fd94b4180ff15901824d20eeba89b4f12853