Create workspace follow-up: Third edition

What does this MR do and why?

This is a third follow-up that addresses feedback received during the development process by product design and the backend team. This MR contains the following changes:

1. It adds the created workspace to the Apollo cache. Otherwise, the Workspace does not appear in the Workspaces list after it is created.
2. It moves the Workspaces Error alert below the submit button.
3. It limits the project search to Public projects.

Screenshots or screen recordings

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Enable the remote development feature flag Feature.enable(:remote_development_feature_flag)
2. You might need to run gdk restart rails-web so rails reconfigure the routes.
3. Open http://gdk.test:3000/-/remote_development/workspaces in your Web Browser.
4. You should see a list of workspaces like the screenshots above.
5. Click the "New workspace" button.
6. Create a workspace by choosing a public project with cluster agents set up.
7. The UI will take you to the Workspaces list and display the Workspace created.

I highly recommend testing these changes in the integration branch if possible !105783 (merged)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #408740 (closed) #408960 (closed)