chore: remove fluent bundle and use esm.sh instead

[OEvgeny]

Fixes #

Changelog Entry

(no changelog entry for internal change)

Description

This removes the fluent-bundle package we used for testing integration with FluentUI theme. Now we use esm.sh CDN instead to retrieve components needed for testing. This also upgrades a portion of tests using the fluent components to new html runner.

Specific Changes

• migrated affected tests to html runner and updated them to use esm.sh instead of locally built fluent-bundle package
• removed fluent-bundle package
• added more tests for dark fluent theme

-

• I have added tests and executed them locally
• I have updated CHANGELOG.md
• I have updated documentation

Review Checklist

This section is for contributors to review your work.

• Accessibility reviewed (tab order, content readability, alt text, color contrast)
• Browser and platform compatibilities reviewed
• CSS styles reviewed (minimal rules, no z-index)
• Documents reviewed (docs, samples, live demo)
• Internationalization reviewed (strings, unit formatting)
• package.json and package-lock.json reviewed
• Security reviewed (no data URIs, check for nonce leak)
• Tests reviewed (coverage, legitimacy)

[compulim]

Should we add a (default) bot icon to copilot theme later? So the "Lorem Ipsum Expert" don't looks too off.

[compulim]

We no longer need the fluent-bundle. But the best part to me is... moving things to /html2/. 🤣

I want to try GitHub Copilot agent to do it... because at some point of time, I saw Git said I did a file rename but I definitely modified the file content as well. I don't have a lot of confidence trusting Git says rename vs. modification... yet.

[OEvgeny]

This PR was partially made with Copilot. Let me get this experiment going.