Display unit tests in generated docs

[gshank]

resolves #472

Description

Adds unit tests to the "Referenced By" sections of a model. Adds new unit test template to skip the compiled_code section.

Checklist

• [x] I have read the contributing guide and understand what's expected of me
• [x] I have signed the CLA
• [x] I have run this code in development and it appears to resolve the stated issue
• [x] I have opened an issue to add/update docs, or docs changes are not required/relevant for this PR
• [x] I have run changie new to create a changelog entry

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Thank you for your pull request! We could not find a changelog entry for this change. For details on how to document a change, see the contributing guide.

[github-actions[bot]]

Thank you for your pull request! We could not find a changelog entry for this change. For details on how to document a change, see the contributing guide.