feat: Build and upload vanilla ESM bundle to assets manager

[muhammad-ali-pk]

Done

• Updated publish-on-release.yaml workflow to bundle and upload ESM to assets manager
• Set up QA in pr.yaml workflow to test release workflow changes

QA

• Verify the build-js and publish-assets actions succeed

Check if PR is ready for release

If this PR contains Vanilla SCSS or macro code changes, it should contain the following changes to make sure it's ready for the release:

• [ ] PR should have one of the following labels to automatically categorise it in release notes:
  • Feature 🎁, Breaking Change 💣, Bug 🐛, Documentation 📝, Maintenance 🔨.
• [ ] Vanilla version in package.json should be updated relative to the most recent release, following semver convention
  • if existing APIs (CSS classes & macro APIs) are not changed it can be a bugfix release (x.x.X)
  • if existing APIs (CSS classes & macro APIs) are changed/added/removed it should be a minor version (x.X.0)
  • see the wiki for more details
• [ ] Any changes to component class names (new patterns, variants, removed or added features) or macros should be listed on the what's new page.

Screenshots

[if relevant, include a screenshot or screen capture]