Add button to close example toolbar

[jmuzina]

Done

Adds a button to the example controls toolbar that closes the controls toolbar. This allows content behind the toolbar to be seen.

Fixes #5283 , WD-13996

QA

• Open any example. Try button.
• Click the "Close" button in the example toolbar.
• Verify the example controls toolbar is removed from view.
• Refresh the page.
• Verify the toolbar is rendered again.

Check if PR is ready for release

If this PR contains Vanilla SCSS code changes, it should contain the following changes to make sure it's ready for the release:

• PR should have one of the following labels to automatically categorise it in release notes:
  • Feature 🎁, Breaking Change 💣, Bug 🐛, Documentation 📝, Maintenance 🔨.
• Vanilla version in package.json should be updated relative to the most recent release, following semver convention:
  • if CSS class names are not changed it can be bugfix release (x.x.X)
  • if CSS class names are changed/added/removed it should be minor version (x.X.0)
  • see the wiki for more details
• Any changes to component class names (new patterns, variants, removed or added features) should be listed on the what's new page.

Screenshots

[webteam-app]

Demo

Jenkins

demos.haus

[jmuzina]

I think I'll make a change on Monday to make the elements in the toolbar have less gap between them on small, so that the toolbar isn't as tall on mobile