Rewrite OutputGroups to be clearer and to use scriptPubKeys
Summary:
Rewrite OutputGroups so that the logic is easier to follow and understand. There is a slight behavior change as OutputGroups will be grouped by scriptPubKey rather than CTxDestination as before. This should have no effect on users as all addresses are a CTxDestination. However by using scriptPubKeys, we can correctly group outputs which fall into the NoDestination case. But we also shouldn't have any NoDestination outputs.
Completes backport of core#20040:
https://github.com/bitcoin/bitcoin/pull/20040/commits/5d4597666d589e39354e0d8dd5b2afbe1a5d7d8e
Depends on D14022.
Test Plan:
ninja all check-all
Reviewers: #bitcoin_abc, PiRK
Reviewed By: #bitcoin_abc, PiRK
Differential Revision: https://reviews.bitcoinabc.org/D14023