Issue 469: Make ControlledDictionary a subclass of Dictionary

[ajnelson-nist]

This Pull Request will resolve all requirements of Issue 469.

Coordination

• [x] Pull Request is against correct branch
• [x] Pull Request is in, or reverted to, Draft status before Solutions Approval vote has passed. (N/A under bugfix workflow)
• [x] CI passes in UCO feature branch
• [x] CI passes in UCO current unstable branch (6d44914)
• [x] CI passes in CASE current unstable branch tracking UCO's unstable as submodule (8d1032c)
• [x] Impact on SHACL validation reviewed for CASE-Examples
• [x] Impact on SHACL validation remediated for CASE-Examples (N/A)
• [x] Impact on SHACL validation reviewed for casework.github.io
• [x] Impact on SHACL validation remediated for casework.github.io (N/A)
• [x] Milestone linked
• [x] Solutions Approval vote logged on corresponding Issue (N/A under bugfix workflow)

[ajnelson-nist]

@sbarnum , @plbt5 , @eoghanscasey , @b0bkaT - this is ready for review. The first to review may merge.