redirect.html.erb fails silently if JavaScript is disabled

Issue summary

A user has JavaScript disabled and tries to install an app by going to /login and entering their shop name. After submitting the /login page they just get a blank page and nothing happens.

• shopify_api version: 13.1.0
• shopify_app version: 21.6.0
• Ruby version: 3.2.1
• Operating system: All

Expected behavior

The user should see an indication that they need to have JavaScript enabled.

Actual behavior

They get a blank screen.

Steps to reproduce the problem

1. Disable JavaScript
2. Go to the /login page of an app
3. Enter a *.myshopify.com domain
4. Submit the form
5. See a blank page
6. View source
7. See that you've been served the redirect.hml.erb page, which contains only an empty div and a link to a redirect.js script.

Blank page:

View source:

Problem file:

https://github.com/Shopify/shopify_app/blob/2a75c07e98ca171aca53ca5af1d9a2fe29489b20/app/views/shopify_app/shared/redirect.html.erb#L10-L22

Start with app/views/shopify_app/shared/redirect.html.erb and reproduce the /login flow with JavaScript disabled. Check the rendered source and ensure the page gives users a visible indication that JavaScript must be enabled instead of showing a blank screen.