feat(admin, admin-ui, medusa-js, medusa-react, medusa): Support Admin Extensions (#4761)

Co-authored-by: Rares Stefan <948623+StephixOne@users.noreply.github.com>
Co-authored-by: Oli Juhl <59018053+olivermrbl@users.noreply.github.com>

packages/admin-ui/tsconfig.json

@@ -4,15 +4,21 @@
     "declarationMap": true,
     "experimentalDecorators": true,
     "emitDecoratorMetadata": true,
+    "lib": ["es2019"],
     "module": "commonjs",
     "moduleResolution": "node",
     "noEmit": false,
     "resolveJsonModule": true,
     "esModuleInterop": true,
     "outDir": "dist",
-    "rootDir": "src",
+    "rootDir": ".",
     "skipLibCheck": true
   },
-  "include": ["src"],
-  "exclude": ["**/node_modules", "ui"]
+  "include": [
+    "src",
+    "tsup.config.ts",
+    "webpack.config.dev.ts",
+    "src/node/webpack/get-webpack-config.ts"
+  ],
+  "exclude": ["node_modules", "ui", "./src/**/__tests__"]
 }