cli: create bitcoin-cli -generate command
Summary:
This is a backport of core#19133 [6/10]
https://github.com/bitcoin/bitcoin/pull/19133/commits/4818124137732540383a29835afa2be41aa55ca8
Depends on D9945
Test Plan:
src/qt/bitcoin-qt -regtest -server src/bitcoin-cli -regtest -generate 8
Reviewers: #bitcoin_abc, majcosta
Reviewed By: #bitcoin_abc, majcosta
Differential Revision: https://reviews.bitcoinabc.org/D9946