changed depth launch to not evaluate dict when and fail when sensor other then oakd is used

[gitisacatsname]

as stated here:
#94

[gitisacatsname]

ah, forgot to state also fixed property name for realsense sensor as this changed since wrapper is out of beta.

[grassjelly]

hi, thanks for the PR. Could we try this instead? It's quite hard to debug that PythonExpression in the future in case it breaks again. I don't have an oak-d so this approach might be less intrusive.

  IncludeLaunchDescription(
      PythonLaunchDescriptionSource(PathJoinSubstitution(
          [FindPackageShare('depthai_examples'), 'launch', 'stereo.launch.py']
      )),
      condition=IfCondition(PythonExpression(['"', LaunchConfiguration('sensor'), '" in "', str(oakd_sensors), '"'])),
      launch_arguments={
          'camera_model': to_oakd_vars.get(LaunchConfiguration('sensor')], "UNKNOWN"),                
      }.items()   
  ),