Fix camera settings in render()

[ratheron]

Previously, setting the cam_id or cam_name didn't do anything when using the renderer (human mode). This PR fixes that by forcing the cam ID after initialization of the renderer.

Known issues: If there will ever be another camera defined by the scene.xml, the user wont be able to move it in the GUI, since we force the camera to be fixed

[amacati]

Is there any way for us to test the changed behavior? Something that failed before and works now?

[ratheron]

This is something you can only see in the renderer. We could write a hard coded test to check some pixels, which could reveal if the correct cam was selected. Not sure if this works though (i.e., if pixels are returned at all). Also, this would be quite brittle, since changing the models or scene could break the test.

[amacati]

We could have an A/B test and check if the view changes correctly. We do something like that in https://github.com/utiasDSL/crazyflow/blob/main/tests/unit/test_visualizations.py

[amacati]

The current ones look decent enough though. Just needs a format fix