Performance/Webpack: Introduces more aggressive code-splitting and other perf improvements (#18544)

* Performance/Webpack: Introduces more aggressive code-splitting and other perf improvements
- Introduces dynamic imports for built-in plugins
- Uses dynamic imports for various packages (rst2html, brace)
- Introduces route-based dynamic imports
- Splits angular and moment into separate bundles

.babelrc

@@ -3,8 +3,11 @@
     [
       "@babel/preset-env",
       {
-		  "targets": { "browsers": "last 3 versions" },
-		  "useBuiltIns": "entry"
+        "targets": {
+          "browsers": "last 3 versions"
+        },
+        "useBuiltIns": "entry",
+        "modules": "false",
       }
     ]
   ]