Camera sensor `topic` param

[23pointsNorth]

Is your feature request related to a problem? Please describe.
When using the exported SDFs with Gazebo, one has to manually add the optional param topic to the Custom Properties. The params added in the UI dialogue for setting the camera sensor include a variety of required and optional params.

Describe the solution you'd like
Adding the optional param topic to the UI in camera sensor.

{
   "type":"String",
   "property_name":"topic",
   "default_value":"${camera_name}/image_raw",
   "description":"Name of topic on which data is published."
}

Describe alternatives you've considered
Setting it up manually per camera sensor.

[hwiedPro]

Hi @23pointsNorth,
please check whether my commit to develop branch solves (at least partially your request)