add gimbal extension and docs

[caomuqing]

Add gimbal extension and docs

What does this pull request do?

It add a gimbal extension allowing the users to add a gimbalized camera to a drone and creates the relevant topic for image publishing and control.

Which issue number does this address: #169

Add videos and images if possible: https://drive.google.com/file/d/1pN0Pxe4nYQL1qs40oZTDqsOXsMrApLPM/view?usp=sharing

How did you implement it?

added a gimbal_stabilizer node in the robot/autonomy/sensors folder.
added gimbal extension folder simulation/isaac-sim/sitl_integration/kit-app-template/source/extensions/airlab.gimbal

Testing

How do you run the tests?
once you run docker compose up docs, follow the docs at http://localhost:8000/docs/docs/robot/autonomy/1_sensors/gimbal/

Did you update the docs (and where)?

Docs are updated via mkdocs.yml and markdown files under docs/. It should render at localhost:8000 when you run docker compose up docs.

[andrewjong]

Great, thank you!