feature zoom focus tracking

[aminballoon]

From this PR -> mavlink/MAVSDK#2094 (comment)
This repository add the camera function to proto

[julianoes]

Thanks for the PR. Are you aware of #320? I'm just worried you might run into conflicts given you're both working on camera things.

[aminballoon]

Thanks for good news . I have read #320 I'm not worried about this PR. These 2 PR should be able to combine because the functions are not duplicated.

[JonasVautherin]

Maybe a question for @julianoes here: how much do those functions overlap with camera params? Is it expected to have an API here for some params, but not all?

[aminballoon]

@JonasVautherin I think it's depend on camera model some camera payload doesn't support Mavlink command they may not be able to use this feature either.

[julianoes]

@JonasVautherin zoom and focus are not implemented using parameters but standardized commands:
https://mavlink.io/en/messages/common.html#MAV_CMD_SET_CAMERA_ZOOM
https://mavlink.io/en/messages/common.html#MAV_CMD_SET_CAMERA_FOCUS

So I think this is ok.

[JonasVautherin]

I know at least two cameras that have zoom and/or focus in the camera definition 😇. The only one that the specs say must be implemented with a message is CAM_MODE, I think. But of course they don't say that those two messages should not be used.

I guess that's part of the MAVLink specs: the user should try to detect (or hardcode) the camera and then hardcode the correct behavior 🙈.

[julianoes]

Yer zoom was added later, as was focus.

[julianoes]

I've edited this a bit. I added the units, and removed the redundant camera prefix.