Add unit and vr tests to Rating

[tomi-msft]

This PR is to add unit and vr tests to Rating. It adds unit tests for Rating, RatingDisplay, and RatingItem, and adds vr tests for Rating and RatingDisplay

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit bb405ac:

Sandbox	Source
@fluentui/react 8 starter	Configuration
@fluentui/react-components 9 starter	Configuration

[fabricteam]

📊 Bundle size report

_{🤖 This report was generated against ad5da7b666f33ecfb5b296ea9bb9824dc9f01662}

[size-auditor]

Asset size changes

Size Auditor did not detect a change in bundle size for any component!

Baseline commit: ec4c7fe368e91c0ba4e2685e21b6d48780124269 (build)

[smhigley]

Left a couple comments on the a11y bits, the other tests look good.

I think it makes sense to add this in a separate PR, but both Rating and Rating display probably need some sort of (value) => string function prop to generate labels for individual rating items and also the display value text.

[tomi-msft]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 4 pipeline(s).