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/src/index.ts

@@ -43,11 +43,6 @@ program
     "Show all logs of underlying commands. Useful for debugging.",
     false
   )
-  .option(
-    "--v2",
-    "Install Medusa with the V2 feature flag enabled. WARNING: Medusa V2 is still in development and shouldn't be used in production.",
-    false
-  )
   .parse()
 
 void create(program.opts())