Optional feature for forced disconnect on unauthorized mqtt31 publish (#2228)
* Introduce configuration variable disconnect_on_unauthorized_publish_v3 to force disconnect on unauthorized publish, even for non MQTT 3.1.1 connections.
* Implementation is now working.
* Add tests for forced disconnect option on unauthorized publish.
* Run code formatter.
* Forgot to add the new test functions to the test groups.
* Add disconnect_on_unauthorized_publish_v3 to list of settable values (vmq_config_cli)
* Simplify code change using a guard sequence, as recommendend in review.
* Add Intellij folder to gitignore.
* Add change description to changelog file.
* Optional feature for forced disconnect on unauthorized mqtt31 publish