## Description
This PR ensures that the default prettier config is used for examples
and templates.
This config is compatible with `prettier@3` as well (upgrading prettier
is bigger change that can be a future PR).
## Changes
- Updated `.prettierrc.json` in root with `"trailingComma": "es5"` (will
be needed upgrading to prettier@3)
- Added `examples/.prettierrc.json` with default config (this will
change every example)
- Added `packages/create-next-app/templates/.prettierrc.json` with
default config (this will change every template)
## Related
- Fixes#54402
- Closes#54409
Converted Blog example over to TypeScript to match the Contribution guidelines.
I also simplified the example by removing `_document.js` and prettier from `package.json`.
## Documentation / Examples
- [X] Make sure the linting passes by running `pnpm lint`
- [X] The examples guidelines are followed from [our contributing doc](https://github.com/vercel/next.js/blob/canary/contributing.md#adding-examples)
Steven