Implement Retain flag for Statestream component

Feature Requests
1

  • Brief description of the device or service. modify the MQTT statestream component ( https://www.home-assistant.io/components/mqtt_statestream/ ) to accept and set the Retain flag

  • Link to the provider or manufacturer’s product or service page. N/A

  • Link to the service or device’s API, along with information as to whether it is public or requires an account or key. (This is extremely important because without a published API, integration of any device or service will be difficult if not impossible!) No API adding MQTT functionality

  • Any other relevant information including examples or GitHub repositories related to the device or service.
    This would allow people to use MQTT Statestream as a sort of variable component where we could store information in an MQTT topic and recall it after a restart of HA alllowing states to persist across HA restarts.