AP_Camera, AP_Mount: Camera Protocol messages don't have component IDs

[nexton-winjeel]

The AP_Camera and AP_Mount libraries have support for some of the messages in the MAVLink Camera Protocol.

However, the handlers for some of these messages (e.g. CAMERA_SETTINGS and CAMERA_INFORMATION) are problematic if there are multiple camera backends:

• these messages do not have IDs (MAVLink intent is to use compid to distinguish components);
• the handlers send these messages from each backend with the MAV_COMP_ID_AUTOPILOT1 compid, so they all appear to come from the same component. This will confuse a GCS.

Originally posted by @nexton-winjeel in #24953 (comment)

[rmackay9]

I haven't looked at the details of this particular issue but we hit a similar issue for MAV_CMD_IMAGE_START_CAPTURE and MAV_CMD_IMAGE_STOP_CAPTURE which led to us adding an extension (see PR ArduPilot/mavlink#328)