#7610263 Support ‘disassociated’ retired themes

For a very small number of themes we have taken over maintenance and by request are renaming them to make it clear they’re no longer related to the original authors. This change informs users what has happened.

See pdgAPm-rI-p2#comment-576 for discussion.

Testing Instructions

1. Add a relevant theme to a test site (A12s you can use the bottom form on the MC ‘Premium Themes: Test Activation’ tool, ping me for a good theme to test)
2. Go to the test site in calypso, navigate to Appearance -> Themes
3. At the top of the themes list press the ‘info’ button on the card showing your current theme
4. This takes you to /theme//
5. Note that no screenshot is displayed. The retirement message is displayed and an additional message is displayed explaining the theme has been renamed.

It should look something like this:

Note that the wording is to be confirmed.

1. Change to a different retired theme, ensure the theme page continues to look as it does in production.
2. Change to a different active theme, ensure the theme page continues to look as it does in production.

Pre-merge Checklist

• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the “[Status] String Freeze” label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?

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