Refactor dashboard codebase to improve modularity (#6330)

* Refactor dashboard codebase to improve modularity

* Simplify feature interface

* Use arrow notation in makeFeature argument types

* Use separate components for node and worker features rather than a single conditionally-rendered component

* Add comments about Ray worker process titles

* Add comments to non-obvious fields in node info API response

python/ray/dashboard/client/package.json

@@ -5,15 +5,18 @@
   "dependencies": {
     "@material-ui/core": "^4.3.3",
     "@material-ui/icons": "^4.2.1",
+    "@reduxjs/toolkit": "^1.0.4",
     "@types/classnames": "^2.2.9",
     "@types/jest": "24.0.18",
     "@types/node": "12.7.2",
     "@types/react": "16.9.2",
     "@types/react-dom": "16.9.0",
+    "@types/react-redux": "^7.1.5",
     "@types/react-router-dom": "^4.3.5",
     "classnames": "^2.2.6",
     "react": "^16.9.0",
     "react-dom": "^16.9.0",
+    "react-redux": "^7.1.3",
     "react-router-dom": "^5.0.1",
     "react-scripts": "3.1.1",
     "typeface-roboto": "0.0.75",