Bump @tootallnate/once and jsdom (#5245)

* Bump @tootallnate/once and jsdom

Removes [@tootallnate/once](https://github.com/TooTallNate/once). It's no longer used after updating ancestor dependency [jsdom](https://github.com/jsdom/jsdom). These dependencies need to be updated together.


Removes `@tootallnate/once`

Updates `jsdom` from 19.0.0 to 28.1.0
- [Release notes](https://github.com/jsdom/jsdom/releases)
- [Changelog](https://github.com/jsdom/jsdom/blob/main/Changelog.md)
- [Commits](https://github.com/jsdom/jsdom/compare/19.0.0...28.1.0)

---
updated-dependencies:
- dependency-name: "@tootallnate/once"
  dependency-version: 
  dependency-type: indirect
- dependency-name: jsdom
  dependency-version: 28.1.0
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

* Fix broken tests after jsdom ESM-only version bump

- Create test/test-setup.mjs as an ES module to support jsdom 22+ (ESM-only)
- Use import { JSDOM } from 'jsdom' instead of require('jsdom')
- Use createRequire to register CSS extension handler (needed for monaco-editor-core CSS imports)
- Use Object.defineProperty for navigator (read-only property in ESM module context)
- Update test:grammars script to use --import ./test/test-setup.mjs instead of --require ./test/test-setup.js

Agent-Logs-Url: https://github.com/microsoft/monaco-editor/sessions/b539df67-cb91-473b-88f4-caa2f9ad207d

Co-authored-by: rzhao271 <7199958+rzhao271@users.noreply.github.com>

* Delete test/test-setup.js (replaced by test/test-setup.mjs)

Agent-Logs-Url: https://github.com/microsoft/monaco-editor/sessions/16b9e5be-7967-42f2-8580-d0426a59173e

Co-authored-by: rzhao271 <7199958+rzhao271@users.noreply.github.com>

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: rzhao271 <7199958+rzhao271@users.noreply.github.com>