Add On-screen Camera controls to Qgroundcontrol app for Herelink

Custom controls have to be added to qgroundcontrol for camera movement and zoom. All the details are added in the attached presentation file. We can discuss the details over a meet.

Repo - https://github.com/CubePilot/qgroundcontrol-herelink
Project details - https://1drv.ms/p/s!AtxS7eQd6P3pi1ed1qRux5mD2oF8?e=Y5E6R5

Code for similar controls using a widget - https://discuss.px4.io/t/how-to-call-sendcommand-from-qml/23610