expose stronger typed SubmitFunction

[ivanhofer]

partially implements #7161

This PR adds stronger type definitions for SubmitFunction to the types genereted inside $types.d.ts. Unfortunately it is currently not possible to distinguish between Success and Invalid with the current Kit helper types. This could be implemented in a future version.

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[dummdidumm]

Thank you! Regarding "not possible to distinguish between success and failure": Wouldn't that be possible if we introduce a new helper type? There's ActionFailure extends the UniqueInterface which means it's possible to know which is which - AwaitedActions already uses this to unpack them. Two new helper types could be used to filter out the fail/success cases.

[ivanhofer]

What I really meant is: there are no helper types present to distinguish between those two.
Technically it is possible :)
I haven't had more time on friday to come up with a solution. I'll try to find some time in the coming days.

[ivanhofer]

@dummdidumm I have added the distinction between success and failure type

[changeset-bot]

🦋 Changeset detected

Latest commit: 1ad8a3b

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

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Name	Type
@sveltejs/kit	Minor

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[dummdidumm]

Thank you!