Set up Workspaces settings page

Issue: FE: Create "Remote Development" group settings... (#444822 - closed)

What does this MR do and why?

Sets up the initial Skeleton of the Workspaces Settings page behind the remote_development_namespace_agent_authorization feature flag.

Important notes

• This feature is an EE-only feature.
• It is behind the remote_development_namespace_agent_authorization therefore I'm not adding changelogs in the commit message.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

How to set up and validate locally

• Enable the remote_development_namespace_agent_authorization feature flag.
• Open the following URL replacing the group's namespace for the one of your preference https://gdk.test:3443/groups/gitlab-org/-/settings/workspaces
• You should see an empty page.

Related to #444822 (closed)