Moving more ARMI testing tools to the testing module

[john-science]

What is the change? Why is it being made?

Here I move more of the ARMI testing tools to the testing module:

• armi/tests/armiRun-SHUFFLES.txt -> armi/testing/resources/armiRun-SHUFFLES.txt
• armi/tests/armiRun-SHUFFLES.yaml -> armi/testing/resources/armiRun-SHUFFLES.yaml
• armi/tests/COMPXS.ascii -> armi/testing/resources/COMPXS.ascii
• armi/tests/smallHexReactor -> armi/testing/reactors/smallHexReactor

This is part of the overall work for creating a armi.testing module as outlined in #1867

SCR Information

Change Type: trivial

One-Sentence Rationale: We would like to create an armi.testing module with a small set of high-quality testing tools.

One-line Impact on Requirements: NA

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Checklist

• This PR has only one purpose or idea.
• Tests have been added/updated to verify any new/changed code.
• The documentation is still up-to-date in the doc folder.
• The code style follows good practices.
• The dependencies are still up-to-date in pyproject.toml.

[john-science]

@opotowsky I ran that downstream test suite and found that this PR made no impact. Success!

[opotowsky]

One non-blocking comment! Approved