Implement GetNewDestination for DescriptorScriptPubKeyMan

Summary:
Backport of Core PR16528 [22/43] : https://github.com/bitcoin/bitcoin/pull/16528/commits/bfdd0734869a22217c15858d7a76d0dacc2ebc86

Depends on D8419

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Subscribers: majcosta

Differential Revision: https://reviews.bitcoinabc.org/D8421