Migrate vega to Panel

[ahuang11]

Do not merge until holoviz/panel#8215 is released

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 47.88%. Comparing base (b4d3677) to head (b92a6c1).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1425      +/-   ##
==========================================
+ Coverage   47.83%   47.88%   +0.05%     
==========================================
  Files         122      122              
  Lines       20430    20379      -51     
==========================================
- Hits         9772     9758      -14     
+ Misses      10658    10621      -37     

☔ 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.