[Admin] Add new users admin store credits page

[MadelineCollier]

Summary

The full store credits flow is taking a bit longer than I originally expected so I am breaking off this piece in an effort to keep PRs small and easy to review.

This PR is for issue: #5824

This migrates the users/:id/store_credits page from the legacy soldius_backend to the new solidus_admin. Again there were no designs so I just tried my best to match to the existing components and layouts.

The edit, create, and invalidate flow will follow in subsequent PRs, but for now they exist as they did before, powered by the soldius_backend.

The attached video shows the functionality visually:

Store.Credits.mov

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[codecov]

Codecov Report

Attention: Patch coverage is 96.29630% with 1 line in your changes missing coverage. Please review.

Project coverage is 89.33%. Comparing base (25a41bf) to head (9f24cce).
Report is 531 commits behind head on main.

Files with missing lines	Patch %	Lines
...lidus_admin/users/store_credits/index/component.rb	95.45%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5887      +/-   ##
==========================================
+ Coverage   89.32%   89.33%   +0.01%     
==========================================
  Files         759      760       +1     
  Lines       17682    17708      +26     
==========================================
+ Hits        15795    15820      +25     
- Misses       1887     1888       +1     

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[tvdeyen]

This could probably be extracted into a UserTabs module, so we do not have to add it to every user index component, no?

[MadelineCollier]

I tried that early on, but had some issues when using a dynamic value for current (eg: current: action_name == "edit". It would work on initial load but then would sometimes be a bit strange/incorrect in its display during certain flows/partial page reload. Once I have the rest of the store credits stuff out of the way I'd be happy to take another crack at it though!