Use tippy.js for context popup (#20393)

By appending the tooltips to `document.body`, we can avoid any stacking context issues caused by surrounding element's CSS.

This uses [tippy.js](https://github.com/atomiks/tippyjs) instead of Fomantic popups. We should aim to replace all Fomantic popups with this eventually and then get rid of the Fomantic `popup` module completely.

package.json

@@ -29,6 +29,7 @@
     "pretty-ms": "7.0.1",
     "sortablejs": "1.15.0",
     "swagger-ui-dist": "4.11.1",
+    "tippy.js": "6.3.7",
     "tributejs": "5.1.3",
     "uint8-to-base64": "0.2.0",
     "vue": "2.6.14",