--Save Physics Objects' Scene Instancing attributes on placement

[jturner65]

Motivation and Context

This PR improves how objects are instanced. It also introduces the ability to save the scene object instance attributes used to place an object to the object itself. This will make it easier in the future to return an object to its initial position.

How Has This Been Tested

All c++ and python tests 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.

[jturner65]

This is here to cater to Articulated Objects, which use a SceneAOInstanceAttributes, which inherits from SceneObjectInstanceAttributes. Nice to have access to the instance attributes cast appropriately for immediate access.

[aclegg3]

LGTM