MQTT JSON issues for doorbell messages
**Describe the bug**
MQTT message is sent as a JSON object. When a JSON object is provided as doorbellMessage in config, message is skipped because it is looking for a full plaintext match rather than specific value in JSON object as expected.

**To Reproduce**
1. Enable doorbell for a camera
2. Set topic for the doorbell MQTT message, set MQTT message to JSON object (via JSON config)
3. Send MQTT message matching the configured topic with a JSON payload that should trigger the doorbell
4. Log message appears saying that message does not match (configured message appears as [object Object])

**Expected behavior**
JSON object provided in doorbellMessage should be compared with incoming message. If incoming message is JSON and contains appropriate properties with appropriate values - doorbell should be triggered

**Logs**
(not available at the moment as I have switched to plain text)

**Screenshots**
N/A

**Environment**
- Node.js Version: v18.16.0 
- Homebridge Version: v1.6.1
- Camera UI Version: v5.0.27
- Operating System: Ubuntu Jammy Jellyfish (22.04.3 LTS) (docker image)
- Browser: Firefox Developer Edition, Safari
