Refactor ContentAnalysis to expose AnalysisList

[atimmer]

Summary

This PR can be summarized in the following changelog entry:

• Exposes AnalysisList to render a plain list of content analysis results.
• Exposes renderRatingToColor which renders a rating received from YoastSEO.js to a color that can be used in CSS.

Relevant technical choices:

• This makes it possible to use the plain list without the headings in different project. I specifically needed it for the YoastSEO.js dev tool.

Test instructions

This PR can be tested by following these steps:

• Open the standalone test tool of yoast-components.
• Verify that the content analysis looks and works the same as before.
• Run the unit tests.
• Verify they pass.

[afercia]

CR 👍

[boblinthorst]

Acceptance: Content analysis looks and works the same in the standalone for develop and this branch, and the unit-tests all pass, as the test instructions described. so 👍