chore(docs): update example and demo copy buttons

[calebpollman]

Description of changes

Updates to the copy buttons used in the demo and example code blocks:

• consolidate copy related buttons in to CopyButton
• update styling to fix issues called out in Docs update: Menu #1905 (comment)

Screenshots
Extra space below horizontal scroll bar. overlap of copy button on horizontal scroll bar:
Before:

After:

Example text visible through copy button:

Copy button spacing when vertical scroll bar visible:

Before:

After:

Issue #, if available

#1905 (comment)

Description of how you validated changes

Manual testing

Checklist

• PR description included
• yarn test passes
• Tests are updated
• No side effects or sideEffects field updated
• Relevant documentation is changed or added (and PR referenced)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 74651e3

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[0618]

if it's only docs change, we don't add changelog

[calebpollman]

if it's only docs change, we don't add changelog

👍 Can we configure the changeset-bot to not run on docs updates?

[wlee221]

👍 Can we configure the changeset-bot to not run on docs updates?

Not yet, I opened a feature request on their repo: changesets/bot#44

[wlee221]

🛥️

[joebuono]

Thanks for picking this task up!