Investigate FocusRects inside ShadowRoots for Fluent React v8

[spmonahan]

Library

React / v8 (@fluentui/react)

Describe the feature that you would like added

Currently, when a Fluent component is rendered inside a ShadowRoot it is properly focused by the browser (i.e., browser follows tab order through the ShadowRoot) but Fluent's FocusRects are not rendered.

Have you discussed this feature with our team

@spmonahan

Additional context

Example: https://codesandbox.io/s/shadow-dom-focus-rects-fluent-v8-o2cu68

NB: Need to update so the Buttons are rendered correctly with Fluent styles.

Validations

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