Closes #27834

This PR changes project panel, outline panel and collab panel
serialization from global to per-workspace, so configurations are
restored only within the same workspace. Handles remote workspaces too.
Opening a new window will start with a fresh panel defaults e.g. width.

Release Notes:

- Improved project panel, outline panel, and collab panel to persist
width on a per-workspace basis. New windows will use the width specified
in the `default_width` setting.