Duplicate "storage" tab to "other storage" [RUN ALL RSPEC] [RUN AS-IF-FOSS]

What does this MR do?

Background

We have an MVC epic for defining another bucket of storage (e.g. uploads, snippets, artifacts), the MVC is a duplicate of the current storage app in Usage Quotas page with a minor changes (different data source and hiding the purchase button).

Changes

The MR duplicates storage_counter/ and its tests to have "Other storage" tab added to Usage Quotas under a feature flag.

Changes beside the duplication:

• Added Vue app initialization in the page-specific entry-points.
• Added "Other storage" tab to haml templates.

Notes:

• The feature flag won't be enabled until the feature is ready and well tested (after all MRs are merged, see plan's table)
• There's a lot of duplication that would be addressed in follow-up MR as part of the issue's development plan.

Plan

Merge Request	Status
Duplicate the Storage tab under a feature flag (Tests and functionality at once)	👈 You are here
Exclude the "purchase more storage" button	⏳ Upcoming
Replace data with new data + update tests	⏳ Upcoming
Replace all duplicated code with original implementation from storage_counter/ or extract it to a shared folder	⏳ Upcoming

Screenshots

Group's Usage Quotas	Profile's Usage Quotas

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • [-] I have included a changelog entry.
  • I have not included a changelog entry because the changes are behind a feature flag.
• [-] 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

Related to #322897