add jest as extension devDep, go back to using makefile foreach syntax

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

extensions/pod-menu/package.json

@@ -14,11 +14,12 @@
   },
   "dependencies": {},
   "devDependencies": {
-    "ts-loader": "^8.0.4",
-    "typescript": "^4.0.3",
-    "webpack": "^4.44.2",
+    "@k8slens/extensions": "file:../../src/extensions/npm/extensions",
+    "jest": "^26.6.3",
     "mobx": "^5.15.5",
     "react": "^16.13.1",
-    "@k8slens/extensions": "file:../../src/extensions/npm/extensions"
+    "ts-loader": "^8.0.4",
+    "typescript": "^4.0.3",
+    "webpack": "^4.44.2"
   }
 }