Replace typeDocExperimentalTagFixer() with TypeDoc's cascadedModifierTags option

[pomek]

🚀 Summary

• Remove the typeDocExperimentalTagFixer() plugin introduced in v55.4.0.
• Configure TypeDoc's built-in cascadedModifierTags option to exclude @experimental, preventing it from cascading to class members that do not explicitly declare it.
• Add a test in ckeditor5-dev-docs verifying that @experimental is absent from the cascadedModifierTags config passed to TypeDoc.
• Update the typedoc-plugins README and changelog entry accordingly.

---

📌 Related issues

• Closes @experimental without inline notice is stripped from API docs members ckeditor5#20039

---

💡 Additional information

• The native cascadedModifierTags option is a simpler and more reliable solution than the custom plugin — TypeDoc handles the filtering itself before the @experimental tag ever reaches the output.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

[pomek]

• Input:
  

• Output:
  

  

[psmyrek]

Btw, have you checked this option? 😅

[pomek]

WFM. Changes in progress.

[pomek]

@psmyrek, WFM. Ready to review.

[pomek]

Results: