Show "Your work" also on Explore pages for now

What does this MR do and why?

As long as the "Explore" pages are reachable only through tabs on the dashboard pages, we should also show the "Your work" sidebar there, to keep a consistent layout.

Later we want to show a new "Explore GitLab" sidebar there instead.

See #384879 (closed)

Screenshots or screen recordings

How to set up and validate locally

• Make sure you have the your_work_sidebar feature flag enabled:

Feature.enable(:your_work_sidebar)

• While logged in, go to http://gdk.test:3000/dashboard/projects. This page already showed the sidebar before.
• Switch from the Yours tab to the Explore tab. The "Your work" sidebar should persist.
• Switch to the Topics tab. The "Your work" sidebar should persist.
• Same for Explore public groups from http://gdk.test:3000/dashboard/groups
• Same for Explore public snippets from http://gdk.test:3000/dashboard/snippets

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.