Sim settings update (taking over for Nakura Mino)

[jrreyna]

Motivation and Context

Taking over this PR from NakuraMino. Here was the original description:

The current habitat_sim.utils.settings.make_cfg() fn is limited to single first person sensors with the uuid color_sensor, semantic_sensor etc.

e.g.

if settings["color_sensor"]:
        color_sensor_spec = create_camera_spec(
            uuid="color_sensor",
            hfov=settings["hfov"],
            sensor_type=habitat_sim.SensorType.COLOR,
            sensor_subtype=habitat_sim.SensorSubType.PINHOLE,
        )

where camera_sensor_spec.position = [0, settings["sensor_height"], 0].

Since many of the examples in examples/colabs/ use a 1st person sensor AND a 3rd person sensor (e.g. https://github.com/facebookresearch/habitat-sim/blob/main/examples/tutorials/nb_python/ECCV_2020_Interactivity.py#L178), it would be best if you could flexibly add multiple cameras through sim_settings.

How Has This Been Tested

This passes CI/CD, and these changes are also tested through pytest tests/*.py. They all pass.

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.