Agents Manager: Restore agent ID and version query param override

[kat3samsin]

Part of #

Proposed Changes

Restore PR that adds agent ID and version query param override broken by PR

Why are these changes being made?

This enables developers to test different agent configurations without code changes by simply adding query parameters to the URL.

Example usage: ?agent=wpcom-workflow-support_chat&version=1.0.25

Testing Instructions

1. Open Media Library
2. Add query parameters to the URL: ?agent=wpcom-workflow-support_chat&version=1.0.25
3. Send a message in the Unified Chat
4. Verify the agent by checking in the Network Tab > filter by https://public-api.wordpress.com/wpcom/v2/ai/agent

5. Test without the agent param it should use wp-orchestrator as default
6. Test Image Studio it should work as expected

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you tested accessibility for your changes? Ensure the feature remains usable with various user agents (e.g., browsers), interfaces (e.g., keyboard navigation), and assistive technologies (e.g., screen readers) (PCYsg-S3g-p2).
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
  • For UI changes, have we tested the change in various languages (for example, ES, PT, FR, or DE)? The length of text and words vary significantly between languages.
• For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-168658

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-168658&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-168658&env=a8c-for-agencies

Dashboard live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-168658&env=dashboard

[matticbot]

This PR modifies the release build for the following Calypso Apps:

For info about this notification, see here: PCYsg-OT6-p2

• agents-manager
• help-center
• notifications
• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug fix/restore-agent-override-query-params on your sandbox.

[t-wright]

I hit the Jetpack auth error again while trying to test image studio flow but was able to complete the rest of the testing steps as described.