Added SSL support

[iNikitaGricenko]

What changes are being made and why?

• Implemented custom SSL Socker Factory (MQTT SSL: Support for self-signed server certificates #39)

---

How the changes have been QAed?

Setup Instructions for unit test

• Run generate_certificates.sh script in docker/ssl folder
• Copy ca.crt file from docker/ssl/certs folder into test/resources/crt
• Uncomment mosquitto-ssl from docker-compose-ci.yml, and run it

yaml

task:
  - id: watch
    type: io.kestra.plugin.mqtt.Publish
    topic: test/trigger
    clientId: kestraProducer
    server: ssl://localhost:8883
    crt: /home/path/to/ca.crt
    serdeType: JSON
    retain: true
    from:
       type: "sensors"
       value: 1.23

[loicmathieu]

LGTM