Upgrade with-redux example to app router (#49994)
### What?
Update **with-redux** example.
### Why?
**with-redux** example have:
- outdated packages
- outdated approaches and relies on **pages** directory
Since **app router** is stable now and is recommended to use, I've updated this example.
### How?
An update includes:
- move example to **app router**
- update **package.json** deps to the latest versions
- modernize jest by switching from **ts-node** to **@swc/jest**
- fix and overhaul **tests**
- modernize **redux** infra
- overhaul example **source code quality**
Co-authored-by: Balázs Orbán <18369201+balazsorban44@users.noreply.github.com>
