The previous method for copying the debug report to the clipboard involved having a hidden `<textarea>`, but this shows up in screen readers and can't be reliably hidden.
To work around this, the button now uses the `clipboard.js` library, which automatically handles browser differences in the Clipboard API, and can load the text to copy from a `data-` attribute on the button.
Props pento, hedgefield, afercia.
Fixes#46647.
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Gary Pendergast