--[BE] - Refactor/cleanup attributes and attributes managers

[jturner65]

Motivation and Context

This PR addresses a few things that I've wanted to take care of for a while, as well as a little bit of groundwork for future PRs. All of these changes are transparent and should have no impact on current Sim execution.

• Rename the base classes for the attributes and the managers to be more in line with naming conventions elsewhere in the code base.
• Add a Configuration comparison override.
• Add the ability to check for duplicate Configurations before adding them as Subconfigs on demand.
• Address a rare edge-case issue during attributes registration where the name that the attributes is saved with can potentially not be the name that is passed to the (child-class-specific) post-registration processing.

How Has This Been Tested

Locally 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 because the hidden values are used as instance-specific, internally-used metadata that are, by design, always unique.

[aclegg3]

LGTM. I don't see any issues.