[examples] Add example using nextjs & @mui/styles as a starter for the migration to v5

[mnajdova]

Closes #29428

The PR adds new example project that can serve as a starting point when migrating to v5. The #29428 revealed that lot of people are struggling with this, so adding the example should hopefully help.

The PR should be merged after #32740, so that we can link it where appropriate.

[mui-bot]

No bundle size changes

Generated by 🚫 dangerJS against ccaf62e

[mnajdova]

cc @siriwatknp could you review from technical point of view?
cc @samuelsycamore this is an example project for people that use Mateiral UI v5 with @mui/styles (JSS) and nextjs, it contains all configuration required for SSR. Where do you think it's best for us to link this in the migration guide?

Should we also link it here - https://mui.com/material-ui/getting-started/example-projects/#main-content ?

[samuelsycamore]

@samuelsycamore this is an example project for people that use Mateiral UI v5 with @mui/styles (JSS) and nextjs, it contains all configuration required for SSR. Where do you think it's best for us to link this in the migration guide?

Good question. Both the "getting started" and the "migrating from JSS" pages contain this text:

One of the biggest changes in v5 is the replacement of JSS for Emotion as a default styling solution.

I think it would make sense to add a line or two in this section on both pages to say that you can check out this example project to see how to upgrade to v5 while continuing to use @mui/styles.

Should we also link it here - https://mui.com/material-ui/getting-started/example-projects/#main-content ?

Definitely!

I think it would also be worthwhile to write a blog post to explain the setup and hopefully catch more frustrated devs looking for a solution on Google. 😁 I'm happy to take that on.

[siriwatknp]

I think we should mark them as latest?

[siriwatknp]

@samuelsycamore I wonder if we need to mention in the migration guide that React 18 upgrade should be done after MUI upgrade?

Currently, we only mention about the minimum version of React

cc @mnajdova does it make sense?

[mnajdova]

React 18 upgrade should be done after MUI upgrade

If you mean: React 18 upgrade should be done after @mui/styles is replaced with one of the alternatives, than yes, good point 👍

[mnajdova]

cc @siriwatknp & @samuelsycamore would be great to push this and #33063 (comment) for next week release :)

[samuelsycamore]

Excellent addition!