Add new empty state to group overview

What does this MR do and why?

Related to #267014 (closed)

Adds a new empty state to the group overview.

Screenshots or screen recordings

With permissions to create subgroup or project

Desktop

Before	After

Mobile

Before	After

Without permissions to create subgroup or project

Desktop

Before	After

Mobile

Before	After

How to set up and validate locally

With permissions to create subgroup or project

• Create a new group and navigate to group overview

Without permissions to create subgroup or project

• Create a new group and navigate to Group information -> Members
• Add a member as a Reporter
• Navigate to /admin/users, find that user you just added, click Impersonate
• Navigate back to the group overview

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.