feat(create-medusa-app): install v2 by default (#7381)

- Remove `v2` option and install V2 starter branch by default.
- Use new `exec` command to seed data
- Install v2 branch of next.js starter if the option is provided.
- Change the opened browser to `localhost:9000/app`.
- Added a bunch of todos for onboarding flows once we have that

packages/cli/create-medusa-app/package.json

@@ -8,6 +8,7 @@
   "license": "MIT",
   "scripts": {
     "dev": "ts-node --esm src/index.ts",
+    "start": "node dist/index.js",
     "build": "tsc",
     "watch": "tsc --watch",
     "prepublishOnly": "cross-env NODE_ENV=production tsc --build"