JSdoc/TS fix of EllipsoidTangentPlane.fromPoints

[zoran995]

The EllipsoidTangentPlane.fromPoints misses a return type, it creates a new instance of EllipsoidTangentPlane. Missed to report this in #8926.

[cesium-concierge]

Thanks for the pull request @zoran995!

• ✔️ Signed CLA found.
• ❔ CHANGES.md was not updated.
  • If this change updates the public API in any way, please add a bullet point to CHANGES.md.
• ❔ Unit tests were not updated.
  • Make sure you've updated tests to reflect your changes, added tests for any new code, and ran the code coverage tool.

Reviewers, don't forget to make sure that:

• Cesium Viewer works.
• Works in 2D/CV.
• Works (or fails gracefully) in IE11.

[hpinkos]

Thanks @zoran995!

[midnight-dev]

@hpinkos @zoran995 Hey guys. I realize this is a bit of a nitpick, but could one of you correct the minor typo in the changelog regarding this PR? (CI skip)

... which didn't listed a return type.