Include excess storage data in the storage endpoint response

What does this MR do?

Part of #255348

Depends on !43322 (merged) and !43462 (merged)

Pass excess storage data for project and namespace in the response of the GraphQL endpoint, getStorageCounter, by using the methods introduced in !43462 (merged). This endpoint is used by the Usage Quotas pages for namespaces and the new fields defined in this MR will only be used in GL.com and will be included conditionally based on the optional parameter, withExcessStorageData. The FE team intends send this new parameter based on the present of a feature flag, additional_repo_storage_by_namespace, and an app setting which will be introduced soon.

Note: We decided not to add a changelog because these new fields are intended only to be used in GL.com and will be requested by the FE using the feature flag and app setting mentioned above. However, we can add one if reviewers feel like it's needed because these fields aren't technically prevented from being using.

Screenshots

Here's an example of the query used via the GraphQL explorer:

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team