Integrate workspaces popover in the repository and file tree views

What does this MR do and why?

It integrates the workspaces popover in the project and repository pages. The workspaces popover allows user to view and manage their workspaces created for the opened project in the GitLab application.

Context This feature is behind a feature flag.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

State	Screenshots
User has workspaces in the current project
User doesn't have workspaces but workspaces are enabled for the current project
User doesn't have workspaces enabled for the current project
Workspaces feature is not available (it is a GitLab CE instance)
Mobile view

How to set up and validate locally

Note Setting up remote development can be a challenging endeavor. If you want to see these changes in your local environment, but don't have enough time to follow these instructions, we can have a pairing session 🙂 .

1. Set up a remote development environment in your GDK.
2. Create a Workspace following these instructions https://docs.gitlab.com/ee/user/workspace/#create-a-workspace.
3. Go to the project overview page, the repository page, or the file viewer.
4. Select the "Edit" dropdown.
5. You should see your workspaces.

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 #416125 (closed)