refactor: Migrate POST /admin/group to Tapir (DEV-1588)

[mpro7]

Pull Request Checklist

Task Description/Number

Issue Number: DEV-1588

PR Type

• build/chore: maintenance tasks (no production code change)
• docs: documentation changes (no production code change)
• feat: represents new features
• fix: represents bug fixes
• perf: performance improvements
• refactor: represents production code refactoring
• test: adding or refactoring tests (no production code change)

Basic requirements for bug fixes and features

• Tests for the changes have been added
• Docs have been added / updated

Does this PR introduce a breaking change?

• Yes

Does this PR change client-test-data?

• Yes

[linear]

DEV-1588 DSP-API: Migrate admin/groups routes to tapir

[swarmia]

✅  Linked to Story DEV-1588 · DSP-API: Expose admin/groups routes with ZIO HTTP
➡️  Part of Epic DEV-1380 · C: DSP-API Introduce ZIO HTTP

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.56%. Comparing base (eac5751) to head (d1ca9d2).
Report is 87 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #3057       +/-   ##
===========================================
+ Coverage   11.74%   88.56%   +76.81%     
===========================================
  Files         246      262       +16     
  Lines       22907    22538      -369     
===========================================
+ Hits         2690    19960    +17270     
+ Misses      20217     2578    -17639     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[BalduinLandolt]

LGTM