Refactor D/I: Move clone class definitions to hierarchy package

[azidar]

Should follow after merging #2488

Contributor Checklist

• [N/A] Did you add Scaladoc to every public function/method?
• [N/A] Did you add at least one test demonstrating the PR?
• [N/A] Did you delete any extraneous printlns/debugging code?
• Did you specify the type of improvement?
• [N/A] Did you add appropriate documentation in docs/src?
• Did you state the API impact?
• [N/A] Did you specify the code generation impact?
• Did you request a desired merge strategy?
• [N/A] Did you add text to be included in the Release Notes for this change?

Type of Improvement

API Impact

Moves some classes into the experimental.hierarchy package, out from internal.BaseModule

Desired Merge Strategy

• Squash: The PR will be squashed and merged (choose this if you have no preference.

Reviewer Checklist (only modified by reviewer)

• Did you add the appropriate labels?
• Did you mark the proper milestone (Bug fix: 3.4.x, [small] API extension: 3.5.x, API modification or big change: 3.6.0)?
• Did you review?
• Did you check whether all relevant Contributor checkboxes have been checked?
• Did you mark as Please Merge?