Closes#12171 and makes more progress towards completing#11421

Changes made

• Refactors the currentuseClipboard functionality for better clarity
  • Also renamed one of the returned properties and added a JSDoc comment to help communicate some of the limitations around it
• Adds functionality for notifying the user of a failed clipboard copy
  • By default, this goes through the global snackbar, but it can be overridden if need be
• Added tests foruseClipboard, both for HTTPS and HTTP-only connections
• Updated the code for ourCodeExample component to ensure that clicking the component doesn't cause the inner button to double-fire
• Figured out a way to add back the anti-flicker styling for the HTTP workaround that got removed by a previous PR

Notes

• The testing setup for this PR is very...unconventional. I would recommend readinguseClipboard.test-setup.ts to get a overview of why things are set up the way they are
• To be on the safe side, in addition to the automated tests, I also tested the HTTP-only functionality on Chrome, Firefox, and Safari. Didn't notice any issues with any of them
• Once this PR is through, I am planning to update the code to useClipboard.js, using the tests to ensure there aren't any regressions
• Also still planning to figure out how to update the Firefox visual bug where the CLI auth panel isn't fully centered
  • Need to look into Emotion docs to see what options there are for declaring multiple browser-specific values for the same style property