Add views and controllers for disable shared Runners on group level

What does this MR do?

Adds views and change controllers in order to disable shared Runners on group level. This is the final effort to implement the changes proposed by #23123 (closed).

This MR is a follow up to !33411 (merged) and !36080 (merged).

This MR should be merged after !36080 (merged) is merged, to prevent any business rules from being broken.

Screenshots

Groups

• Both pictures show the same screen, but the second one is zoomed out to see the whole context.

Projects

• This picture shows what happens to a project's CI / CD view if its parent group does not allow shared Runners (both pictures show the same screen, but the second one is zoomed out to see the whole context).

Are there points in the code the reviewer needs to double check?

No.

Does this MR meet the acceptance criteria?

• Documentation created/updated - N/A
• Added tests for this feature/bug
• In case of conflicts with master - no conflicts

What are the relevant issue numbers?

#23123 (closed)