BREAKING CHANGE: Make `react-is` a peer dependency

[eps1lon]

Description

Make react-is a peer dependency instead of a direct dependency

Related Issue

Motivation and Context

react-is needs to be the same version as the used version of React. So far these dependencies could be out of sync since the related internals didn't changed. However, in React 19 related internals did change. Using react-is<19 would not recognize elements from react>=19 and vice versa. So generally, react-is should be installed by library users just like React. That way, users can make sure the versions match without having to resort to resolutions or overrides which wouldn't even work for libraries.

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] I have added tests to cover my changes.
• [x] I have added a storybook story or extended an existing story to show my changes

[ckifer]

uhh I think this PR was made from the wrong branch. Can you try switching to 3.x and then make the change?

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 95.56%. Comparing base (85b29df) to head (0051d8c). Report is 3 commits behind head on 3.x.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## 3.x #4541 +/- ## ======================================= Coverage 95.55% 95.56% ======================================= Files 116 116 Lines 22220 22230 +10 Branches 3057 3057 ======================================= + Hits 21233 21243 +10 Misses 981 981 Partials 6 6 ```

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