Update Changesets and experimental release flow

[markdalgleish]

This adds the new packages to the Changesets config, reimplements the Changesets patch from Remix, and updates the experimental flow to be manually triggered via GitHub, just like Remix.

As part of this, the version script has been updated to handle the new packages, and has been streamlined a bit due to the use of workspace dependencies which means we no longer need to manually bump our dependency versions.

Note that this will need a NIGHTLY_PAT value to work correctly.

[changeset-bot[bot]]

⚠️ No Changeset found

Latest commit: 2b4dbab6ece202de0a2978fdf89a8d820b5069dc

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

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