Implement ChaikinSmoothing for Geometry

[wtchen]

• [x] I agree to follow the project's code of conduct.

• [x] I added an entry to CHANGES.md if knowledge of this change could be valuable to users.

  Implements https://github.com/georust/geo/issues/930

Supports calling chaikin_smoothing on Geometry. If the variant has a ChaikinSmoothing implementation, call the method. Otherwise, just clone the geometry.

[frewsxcv]

@wtchen Thank you! Can you add an entry to CHANGES.md? And address the linting errors in CI

[wtchen]

Done, I fixed linting errors and added an entry to CHANGES.md. Can you review again @frewsxcv? 🙂