perf(cache): optimize _serializeArgList key generation

[tomas-zijdemans]

Reduce overhead in _serializeArgList.ts by replacing the assertWeakKey helper with a direct WeakRef check, using a Set instead of an array for key tracking, and cutting redundant map lookups.

Improved the test coverage.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.02%. Comparing base (6df7f21) to head (f680890).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7044   +/-   ##
=======================================
  Coverage   94.01%   94.02%           
=======================================
  Files         627      627           
  Lines       50029    50028    -1     
  Branches     8807     8807           
=======================================
+ Hits        47037    47039    +2     
+ Misses       2413     2411    -2     
+ Partials      579      578    -1     

☔ 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.