Add a CopyButton component

[PaulioRandall]

What does this change?

Adds a <CopyButton> component.

Why?

To enable quick copy of specific content to clipboard on click.

How is it tested?

Storybook

How is it documented?

Storybook

Are light and dark themes considered?

Yes

Is it complete?

• [x] Have you included changeset file?
• [x] If this adds a new component, is it exported via index.js?