Add and implement codegen in hello-world

[juanpprieto]

WHY are these changes introduced?

hello-world template is not defaulting to using codegen

WHAT is this pull request doing?

• adds codegen flag
• use generated codegen type on root.tsx

[juanpprieto]

@frandiox any idea why the shopify hydrogen codegen-unstable is failing to find any queries during CI?.

I changed the build command to shopify hydrogen codegen-unstable && shopify hydrogen build to ensure the types get generated before the build and typecheck runs which works ok locally.

There's a suitable query at root.tsx that works ok on local. I'm trying to see if we can avoid tracking storefrontapi.generated.d.ts on the hello-world template

[frandiox]

@juanpprieto I'm adding the --codegen-unstable flag to the build command here, and also ensuring we remove that flag for JS projects from the npm build script.

I've made a change there with query paths that might fix the issue you have on CI. Not sure but you can give it a try.

[michenly]

@juanpprieto I am going to close this PR since we are talking about removing Hello world. Feel free to re-open and re-work the PR if needed.