Draft: [Spike] Extend SM Seat Cost Management MVC from SaaS

What does this MR do and why?

Issue: https://gitlab.com/gitlab-org/gitlab/-/issues/431874.

This is a spike to test the feasibility of implementing https://gitlab.com/groups/gitlab-org/-/epics/11996 in Self-Managed instances, by extrapolating from the existing SaaS implementation.

This spike has done the following:

• Explore how much effort it would take to make implementation namespace-agnostic
• Ensure current CodeSuggestionsUsage Vue root component can be viewed in Self-Managed instances
• Ensure current CodeSuggestionsUsage Vue root component can also be used in the Admin Area
• Check if hand-raise functionality can be skipped (in case we need to do that)

Screenshots or screen recordings

N/A

How to set up and validate locally

N/A

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.