chore: Update codeowners to @MetaMask/core-platform

[Mrtenz]

This updates the codeowners to @MetaMask/core-platform.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.26%. Comparing base (fb11d7a) to head (e71615b).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3544   +/-   ##
=======================================
  Coverage   98.26%   98.26%           
=======================================
  Files         411      411           
  Lines       11637    11637           
  Branches     1814     1814           
=======================================
  Hits        11435    11435           
  Misses        202      202           

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

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.