Core: Use named exports in src/

[mgol]

Summary

Fixes gh-5262

Checklist

• New tests have been added to show the fix or feature works
• If needed, a docs issue/PR was created at https://github.com/jquery/api.jquery.com

[mgol]

   raw     gz Compared to main @ 8be4c0e4f89d6c8f780e5937a0534921d8c7815e      
   -11    -30 dist/jquery.min.js                                               
   -11    -10 dist/jquery.slim.min.js                                          
   -11    -32 dist-module/jquery.module.min.js                                 
   -11    -10 dist-module/jquery.slim.module.min.js