Add fetcher data layer

[brophdawg11]

Dependent on #10960

Adds a fetcher data layer to RouterProvider to setup the 3rd (and final) PR for this work (a future flag to change the fetcher cleanup/persistence behavior)

• Implements the updated version of 🗺️ fetcher, submit, and Form Changes remix#7698
• 2nd of 3 PRs to supersede Add support for fetcher key specification and persistence #10945

[changeset-bot]

🦋 Changeset detected

Latest commit: a9c1886

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

Name	Type
react-router-dom	Patch
react-router	Patch
react-router-dom-v5-compat	Patch
react-router-native	Patch

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[brophdawg11]

Fetcher data lives in the React layer now, and we use ref counting via register/unregister to know when to remove from fetcherData

[brophdawg11]

Fetcher data hand-off from the router to the React data layer

[brophdawg11]

I think we're OK using a ref here but I need to bang on some edge cases to be sure - all tests and such pass as-is which is reassuring. The idea is that anytime a fetcher.data needs to update - a fetcher will have changed state which will be what triggers the re-render, and we don't need useState version of fetcherData.

[github-actions]

🤖 Hello there,

We just published version 6.18.0-pre.0 which includes this pull request. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!

[github-actions]

🤖 Hello there,

We just published version 6.18.0 which includes this pull request. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!