Simplify add cluster view (#2716)

- Only shows editor, and will save all text to file

- Reports some validation errors, but doesn't block the add cluster
  button

- Cleanup kube helpers to facilitate clearer FS interactions

Signed-off-by: Sebastian Malton <sebastian@malton.name>

package.json

@@ -203,6 +203,7 @@
     "handlebars": "^4.7.7",
     "http-proxy": "^1.18.1",
     "immer": "^8.0.1",
+    "joi": "^17.4.0",
     "js-yaml": "^3.14.0",
     "jsdom": "^16.4.0",
     "jsonpath": "^1.0.2",
@@ -273,7 +274,7 @@
     "@types/mini-css-extract-plugin": "^0.9.1",
     "@types/mock-fs": "^4.10.0",
     "@types/module-alias": "^2.0.0",
-    "@types/node": "^12.12.45",
+    "@types/node": "12.20",
     "@types/npm": "^2.0.31",
     "@types/progress-bar-webpack-plugin": "^2.1.0",
     "@types/proper-lockfile": "^4.1.1",