Adds a GetNewChangeDestination that has the same objective as GetNewDestination
https://github.com/bitcoin/bitcoin/pull/16237/commits/8e7f930828a9f8f9be1c90ff45e3fdfef1980eaf
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Depends on D6717
Concludes backport of Core [[https://github.com/bitcoin/bitcoin/pull/16237 | PR16237]]