[pulsar-io-rabbitmq] Added integration test for RabbitMQ. (#6033)
Fixes https://github.com/apache/pulsar/issues/5920
### Motivation
The current RabbitMQ connector lacks an integration test.
### Modifications
Adds an integration test for the RabbitMQ connector(both source and sink):
- A container definition using `rabbitmq:3.8-management` as suggested.
- A RabbitMQ source tester, which provides configurations for the RabbitMQ source connector and publishes messages to the RabbitMQ.
- A RabbitMQ sink tester, which provides configurations for the RabbitMQ sink connector and consumes messages from the RabbitMQ for verification.
- A test case that invokes the testers with the current test framework.
### Verifying this change
This change added tests and can be verified as follows:
*(example:)*
- *Added integration tests for the RabbitMQ connector*
6 files changed
