feat: use list for example prompts

[DavidSpriggs]

Description:

This pull request updates how example prompts are managed in the Hub Assistant configuration, switching from a simple array of strings to a list of keyed objects with labels. This enables more flexible editing and better UI support. The changes include schema updates, transformation logic in the HubSite class, UI schema adjustments, and new tests to ensure correct behavior.

Hub Assistant example prompts improvements

• Updated the HubItemEntitySchema so that assistant.examplePrompts is now an array of objects, each with a key and a label, instead of an array of strings. (packages/common/src/core/schemas/shared/HubItemEntitySchema.ts)
• Added transformation logic in HubSite.toEditor and HubSite.fromEditor to convert between string arrays and object arrays for examplePrompts, ensuring compatibility between storage and editing formats. (packages/common/src/sites/HubSite.ts)

Testing and coverage

• Added and updated tests to verify the transformation between string arrays and object arrays for examplePrompts, ensuring round-trip integrity. (packages/common/test/sites/HubSite.spec.ts, packages/common/test/sites/_internal/SiteUiSchemaAssistant.spec.ts)

Instructions for testing:

Closes Issues: # (if appropriate)

1. Updated meaningful TSDoc to methods including Parameters and Returns, see Documentation Guide

2. Either ran npm run changeset or this change does not require a release.

3. These changes have been verified by QA using a ?uiVersion that includes a PR-Preview of this branch and the v_req label has been applied to the issue.

4. OD-UI E2E tests pass against these changes using a ?uiVersion that includes a PR-Preview of this branch

[changeset-bot]

🦋 Changeset detected

Latest commit: 01bf3ac

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

This PR includes changesets to release 1 package

Name	Type
@esri/hub-common	Patch

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[tomwayson]

LGTM