Fixed Kafka integration to correctly publish and get messages

Fixed Kafka integration to correctly publish and get messages:

• Fixed Kafka producer and consumer to correctly serialize/deserialize send Event with event envelope.
• Upgraded Kafka images to the latest 7.0.1 version.
• Added a basic test for Kafka Producer.
• Switched Kafka UI from landoop/kafka-topics-ui to landoop/kafka-ui.

See details in #120.

Besides that:

• Removed obsolete IIS express run profiles.
• Fixed async method signatures in tests.
• Fixed copy/paste naming issues in Cancel Shopping Carts API tests.

See details in #122.