Add: Image resizing & channel reordering

Likely via OpenCV, as it supports multiple resizing policies.

* [Docs](https://docs.opencv.org/3.4/da/d54/group__imgproc__transform.html#ga47a974309e9102f5f08231edc7e7529d)
* [Tutor](https://docs.opencv.org/3.4/da/d6e/tutorial_py_geometric_transformations.html)

Splitting channels:

* [Docs](https://docs.opencv.org/3.4/d2/de8/group__core__array.html#ga0547c7fed86152d7e9d0096029c8518a)

Start by reviewing the linked OpenCV documentation for resizing policies and channel splitting, then inspect the repository's existing tensor and image APIs. Done means the library supports image resizing with the intended policies and channel reordering, with behavior compatible with its supported tensor workflows.

Written by the indexing model from the issue text.