Add `Shared groups` tab to group overview

What does this MR do and why?

Related to #378629 (closed)

Adds a Shared groups tab to the group overview. This will show groups to which the group members gained access through the Invite a group action.

References

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• #378629 (closed)

MR acceptance checklist

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Screenshots or screen recordings

With shared groups

Shared groups empty state

Shared projects empty state

Updated to be consistent with shared groups empty state

How to set up and validate locally

1. Go to a group -> Manage -> Members
2. Click Invite a group
3. Choose a group and invite that group
4. Go to the group you just invited
5. Click on the Shared groups tab