add support in Dropdown for creating new options using allowCreateOptions prop

[anserwaseem]

Describe your changes

• Added support in the Dropdown widget for creating new options via the allowCreateOptions prop.
• When a user types a new option, it is now added to the dropdown and selected automatically.
• To ensure the form's onChange (or Ant Design's onFieldsChange) fires consistently, we introduced a helper that leverages Ant Design's internal RC_FORM_INTERNAL_HOOKS.dispatch.

⚠️ Note: This relies on Ant Design’s private API (RC_FORM_INTERNAL_HOOKS), which may change in future versions.
Alternative approaches like Form.useWatch were considered, but were rejected due to performance trade-offs.
This implementation keeps the change localized to the Dropdown widget and avoids diffing the entire form on every update.

Screenshots [Optional]

er-1103.mov

Issue ticket number and link

Closes #1103

Checklist before requesting a review

• 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

[changeset-bot]

🦋 Changeset detected

Latest commit: 2b90498

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 2b90498):

https://react-kitchen-sink-dev--pr1107-1103-support-creatin-lczdiq3l.web.app

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