[tests] skip rpc_zmq functional test when python3 zmq lib is not present

Also refactors zmq-related test skipping logic into distinct functions.

test/functional/test_framework/test_framework.py

@@ -475,3 +475,20 @@ class SkipTest(Exception):
     """This exception is raised to skip a test"""
     def __init__(self, message):
         self.message = message
+
+
+def skip_if_no_py3_zmq():
+    """Attempt to import the zmq package and skip the test if the import fails."""
+    try:
+        import zmq  # noqa
+    except ImportError:
+        raise SkipTest("python3-zmq module not available.")
+
+
+def skip_if_no_bitcoind_zmq(test_instance):
+    """Skip the running test if bitcoind has not been compiled with zmq support."""
+    config = configparser.ConfigParser()
+    config.read_file(open(test_instance.options.configfile))
+
+    if not config["components"].getboolean("ENABLE_ZMQ"):
+        raise SkipTest("bitcoind has not been built with zmq enabled.")