Use clippie module to copy to clipboard (#23801)

Externalize clipboard copying to the
[clippie](https://github.com/silverwind/clippie) module which I feel I
can maintain outside this repo for shared benefit with my other
projects.

The module is feature-equivalent to the previous code and has one
improvement where it sets `aria-hidden` on the fallback textarea,
preventing screen readers from picking it up. Also it support `Array` of
`content` as well to copy multiple items at once, in case it's ever
needed.

package-lock.json

@@ -19,6 +19,7 @@
         "add-asset-webpack-plugin": "2.0.1",
         "ansi-to-html": "0.7.2",
         "asciinema-player": "3.2.0",
+        "clippie": "3.1.4",
         "css-loader": "6.7.3",
         "dropzone": "6.0.0-beta.2",
         "easymde": "2.18.0",
@@ -2762,6 +2763,11 @@
         "url": "https://github.com/chalk/strip-ansi?sponsor=1"
       }
     },
+    "node_modules/clippie": {
+      "version": "3.1.4",
+      "resolved": "https://registry.npmjs.org/clippie/-/clippie-3.1.4.tgz",
+      "integrity": "sha512-jrW6sG1zcTEQr5MtCXJzszNmHWV9Fkaco8sAqFeuOApNFP/lRFcUi4JABMmxBJwFZLIvbw2BY3G5E+BjBqZMdQ=="
+    },
     "node_modules/cliui": {
       "version": "7.0.4",
       "resolved": "https://registry.npmjs.org/cliui/-/cliui-7.0.4.tgz",