Robots in hablab

[zachavis]

Motivation and Context

This PR removes robot scripts (Fetch) and test cases from habitat-sim, since they were migrated to habitat-lab (#888). This helps to decouple habitat-sim from the definition of a robot, allowing users to use higher level wrappers like habitat-lab to more easily handle configuring embodied agents.

How Has This Been Tested

The robot scripts were removed from habitat-sim and into a local copy of habitat-lab; In habitat-lab, examples/interactive_play.py script ran with Fetch loaded and no issues, and pytest test/test_robot_wrapper.py ran with both tests passing.

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have completed my CLA (see CONTRIBUTING)
• I have added tests to cover my changes.
• All new and existing tests passed.

[aclegg3]

Looks good, thanks for refactoring this.