feat!: drop standalone legacy browser <script> & window object usage

[ghiscoding]

⚠️ Breaking Change

• drop legacy browser <script> (previously available in dist/browser and via CDN)
  • the end user will now have to use modern approach like <script type="module">import { createWorkbook, downloadExcelFile } from 'excel-builder-vanilla'; // ... </script> or load from CDN
• stop using the window object to store things

For a more modern approach, we should stop using the window object as a local variable to store the ExcelBuilder instance itself. That was the legacy approach of JavaScript libraries and we should go away from that approach. This should bring positive changes to the end user, less memory usage (because we no longer override the window object) and a more modern approach

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.9%. Comparing base (addbca1) to head (8658f49).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #164   +/-   ##
=====================================
  Coverage   99.9%   99.9%           
=====================================
  Files         25      25           
  Lines       1803    1803           
  Branches     349     349           
=====================================
  Hits        1801    1801           
  Misses         2       2           

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[github-actions]

🎉 This pull request is included in version 5.0.0 📦
🔗 The release notes are available at: GitHub Release 🚀