Generate dynamic env types

[Rich-Harris]

Closes #6202.

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[changeset-bot]

🦋 Changeset detected

Latest commit: 5d50358

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

This PR includes changesets to release 2 packages

Name	Type
@sveltejs/kit	Patch
create-svelte	Patch

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[tcc-sejohnson]

Suggested change

	[breaking] remove App.PrivateEnv and App.PublicEnv in favour of generated types
	[breaking] remove App.PrivateEnv and App.PublicEnv in favor of generated types

Filthy european

[Rich-Harris]

🇬🇧

[Conduitry]

Suggested change

	[breaking] remove App.PrivateEnv and App.PublicEnv in favour of generated types
	[breaking] remouve App.PrivateEnv and App.PublicEnv in favour of generated types

[Rich-Harris]

🇬🇧

[tcc-sejohnson]

All joking aside, LGTM.

edit: Assuming Safari issues are just flakiness