test: Add resendwallettransactions functional tests
Summary: Backport core's PR11000
Test Plan:
make check && ./test/functional/test_runner.py resendwallettransactions
Reviewers: #bitcoin_abc, matiu
Reviewed By: #bitcoin_abc, matiu
Subscribers: teamcity
Differential Revision: https://reviews.bitcoinabc.org/D1060