Add typing for effect cleanup

[billybimbob]

The effect function signature is changed in order to more closely match the useSignalEffect signature, and also remove the ambiguity of the unknown typing.

The useSignalEffect hook also now properly passes along the cleanup function.

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🦋 Changeset detected

Latest commit: 50fc3e2bc092457a58351b124bf880767fa18780

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

This PR includes changesets to release 1 package

Name	Type
@preact/signals-core	Patch

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