Fix trace toggling for multiple vehicles

[Rajat Singhal (rajat2004)]

Fixes: #4260

About

Now tracing gets enabled for all the vehicles
TODO

• Cleanup of SimHUD code
• Support tracing in Car vehicle (Possibly in a separate PR)

How Has This Been Tested?

Using the Pythonclient/multirotor/multi_agent_drone.py script and settings

Screenshots (if appropriate):

[Rajat Singhal (rajat2004)]

ZiMMy From #4274 looks like a new release is going to happen soon. Is it possible to have this PR included as well?

[David Zimmermann (zimmy87)]

Thanks for fixing this this Rajat Singhal (@rajat2004)! Tested locally and this works for me just fine. Left one comment about cleaning up the Unity wrapper. Will talk with the team about whether to include this in the next release.

[David Zimmermann (zimmy87)]

getSubwindowCameraType, getSubwindowCameraType, getSubwindowVisible, and setSubwindowVisible are also defined here. Is there any reason to not clean up the Unity wrapper as well?

[Rajat Singhal (rajat2004)]

Main reason was that I currently don't have a working Unity installation, going through that code, none of the subwindow code in Unity SimHUD.cpp seems to be actually used, and the subwindows are created in AirsimHUDScript.cs
Will try to go through it a bit more

[David Zimmermann (zimmy87)]

I have a working Unity installation, so I decided to commit this cleanup change after testing that subwindows still functioned normally in my Unity build. Once I get this merged, I'll include it in the next release.

[David Zimmermann (zimmy87)]

Thanks for submitting this PR Rajat Singhal (@rajat2004)! Moving ahead with merging.

[Rajat Singhal (rajat2004)]

Thanks a lot David Zimmermann (@zimmy87) for the Unity changes! I'll get my old setup working over the weekend, sorry for this