add ManagedArticulatedObject attribute for link_id to object_id map

[aclegg3]

Motivation and Context

This PR adds link_ids_to_object_ids python property and getLinkIdsToObjectIds function to python and C++ ManagedArticulatedObject APIs respectfully.

We have had link_object_ids for while providing the opposite mapping. However, collision detection, raycasting, etc... opertate primarily on object_ids. If we want to know the object_id for a link in order to check it, we had to create an inverted map like:

links_to_obj_ids = {v: k for k, v in ao.link_object_ids.items()}

which is a pain.

How Has This Been Tested

Added a unit test for the maps in both directions.

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.

[jturner65]

lgtm