Adding axial expansion support for CRAs

[albeanth]

Description

This PR adds support for axial expansion of pin-type control rod assemblies (CRAs). The primary assumption with this approach is that all components axially expand upwards. This is a valid assumption as long as the z-elevation of the control bundle tip is relative to itself; i.e., simply placing the bundle at a prescribed z-elevation. This is in contrast to the case where the z-elevation of the control bundle is relative to the control rod driveline. In this case, the downward expansion of components within the control bundle becomes important and this approach is invalidated.

This PR will remain in draft state until 1) unit tests are added to support CRA expansion, and 2) the effects on downstream applications have been quantified.

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Checklist

• This PR has only one purpose or idea.
• Tests have been added/updated to verify that the new/changed code works.

• The code style follows good practices.
• The commit message(s) follow good practices.

• The release notes (location doc/release/0.X.rst) are up-to-date with any bug fixes or new features.
• The documentation is still up-to-date in the doc folder.
• The dependencies are still up-to-date in setup.py.

[keckler]

Easy enough. You need to add something to the changelog. I imagine this might change some results and confuse people.

[albeanth]

Coverage drop appears to be coverage spray....

[john-science]

@albeanth This is waiting on a downstream project. So, short-term holding pattern.

[albeanth]

This PR is ready, but I am converting to draft while we figure out downstream merge dependencies.