Speedup the ComputeClosestPoint query for a single 3D Point

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](https://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](https://www.open3d.org/docs/release/) and the [latest documentation](https://www.open3d.org/docs/latest/) (for `main` branch).

### Proposed new feature or change

Adding a function ComputeClosestPoint(const Eigen::Vector3d& query_point) which is used to computes the closest point on the surface of the scene to a single query point.

I created a PR for this feature request.

### References

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### Additional information

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