include selectedPage of EnsembleMenu in js context and bindings

[anserwaseem]

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• I have performed a self-review of my code
• I have added tests
• I have added a changeset pnpm changeset add
• I have added example usage in the kitchen sink app

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🦋 Changeset detected

Latest commit: 50a6cab

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

This PR includes changesets to release 4 packages

Name	Type
@ensembleui/react-kitchen-sink	Patch
@ensembleui/react-runtime	Patch
@ensembleui/react-preview	Patch
@ensembleui/react-starter	Patch

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Visit the preview URL for this PR (updated for commit 50a6cab):

https://react-kitchen-sink-dev--pr1120-menu-selectedpage-m4u840lh.web.app

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