Tests for zmqpubrawtx and zmqpubrawblock
Summary: Backport core's PR10552
Test Plan:
./test/functional/test_runner.py zmq_test
Reviewers: #bitcoin_abc, schancel
Reviewed By: #bitcoin_abc, schancel
Subscribers: teamcity
Differential Revision: https://reviews.bitcoinabc.org/D1156