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