MXS-2271 Monitor config name and instance name are parameters of createInstance()

Also adds/moves some comments from previous entrypoints. Name and module
are now constant fields.

server/modules/monitor/mariadbmon/test/test_cycle_find.cc

@@ -90,7 +90,7 @@ int main()
 }
 
 MariaDBMonitor::Test::Test(bool use_hostnames)
-    : m_monitor(new MariaDBMonitor())
+    : m_monitor(new MariaDBMonitor("TestMonitor", MXS_MODULE_NAME))
     , m_use_hostnames(use_hostnames)
 {
 }