fix: deepkeyandvalue behavior in union types

[mdm317]

🎯 Changes

fixes #1813

Fix DeepKeysAndValues to return nullish values instead of never when the value type is nullish

• main

type Test = DeepKeysAndValues<{ id : undefined }>
//        ^? never

ts playground

• this branch

type Test = DeepKeysAndValues<{ id : undefined }>
//        ^? { key : 'id', value: undefined}

---

Due to the above change, I replaced DeepKeysOfType with DeepKeysOfNonNullableType in the group API.

#2057 (comment)

✅ Checklist

• I have followed the steps in the Contributing guide.
• I have tested this code locally with pnpm test:pr.

🚀 Release Impact

• This change affects published code, and I have generated a changeset.
• This change is docs/CI/dev-only (no release).

Change

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🦋 Changeset detected

Latest commit: 81806f8

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

This PR includes changesets to release 13 packages

Name	Type
@tanstack/react-form	Patch
@tanstack/solid-form	Patch
@tanstack/form-core	Patch
@tanstack/react-form-nextjs	Patch
@tanstack/react-form-remix	Patch
@tanstack/react-form-start	Patch
@tanstack/angular-form	Patch
@tanstack/form-devtools	Patch
@tanstack/lit-form	Patch
@tanstack/svelte-form	Patch
@tanstack/vue-form	Patch
@tanstack/react-form-devtools	Patch
@tanstack/solid-form-devtools	Patch

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[mdm317]

Since the previous behavior inferred never when the value was nullish,
the changes were updated to continue inferring never for nullish value types.

[mdm317]

After changing DeepKeysAndValues to include nullish values, a bug was introduced in the group API when using DeepKeysOfType.

When the value type is nullish, it previously evaluated as:

Extract<never, nullish | TValue>

However, after the change, it became:

Extract<nullish, nullish | TValue>

which now returns nullish.
To resolve this issue, I implemented a new utility type to correctly infer TFields in the group API.