AP_Camera only send feedback message if autopilot is triggering the camera directly

#### Issue details
Currently every time the autopilot sends a trigger message the feedback message is also sent. By the pixhawk. In cases where the camera is actually triggered by a secondary camera controller or a companion computer. Then that component should be responsible for sending the feedback message. Only in the case where there is no other component to trigger the camera, or if the feedback pin is used on the pixhawk, should the feedback message be sent.

I propose a parameter to enable or disable sending the feedback message.

#### Platform
[X] All
[ ] AntennaTracker
[ ] Copter
[ ] Plane
[ ] Rover
[ ] Submarine

#### Airframe type
All Airframes

#### Hardware type
Not relevant to hardware

Start by locating AP_Camera and the code that sends autopilot trigger and feedback messages. Trace how direct triggering, secondary controllers, companion computers, and the Pixhawk feedback pin are distinguished. Done means a configurable parameter prevents duplicate feedback while retaining feedback for direct or pin-based triggering; no file or test is named in the issue.

Written by the indexing model from the issue text.