text: Title: [Tracker] Move functions that are not tests from `tests` to `testing`
  Body: We have a bunch of helper functions that are aside from the tests which should be moved to `testing`. The general rule is, if the code isn't a test, or something related to pytest (fixture, some config, etc) it should be moved to the `testing` directory.
  
  This issue will work as a tracker to map some of these functions, feel free to help us find others and/or help us move them to `testing`.
  
  The goal here is to reorganize our test suite. If you have any questions, you can call us and/or ask on our Slack page too [![Slack](https://img.shields.io/badge/Slack-4A154B?logo=slack&logoColor=white)](https://join.slack.com/t/kornia/shared_invite/zt-csobk21g-2AQRi~X9Uu6PLMuUZdvfjA)
  
  
  _Originally posted by @johnnv1 in https://github.com/kornia/kornia/pull/2745#discussion_r1461253082_
  
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  You can choose anyone below, or find new ones. You don't have to worry about separating all the tests in a file into a single PR
  
  - [ ] Hardone, maybe needs to reimplement part of it - https://github.com/kornia/kornia/blob/ce434e467faf617604bb3383cf78cd0b79f59dbd/tests/augmentation/test_augmentation.py#L64
  - [ ] nerf - here are one of the functions I have found around nerf tests, maybe have more, is valid to re-check it :)
    - https://github.com/kornia/kornia/blob/ce434e467faf617604bb3383cf78cd0b79f59dbd/tests/nerf/test_rays.py#L20
    - https://github.com/kornia/kornia/blob/ce434e467faf617604bb3383cf78cd0b79f59dbd/tests/nerf/test_rays.py#L69
    - https://github.com/kornia/kornia/blob/ce434e467faf617604bb3383cf78cd0b79f59dbd/tests/nerf/test_rays.py#L81
    - https://github.com/kornia/kornia/blob/ce434e467faf617604bb3383cf78cd0b79f59dbd/tests/nerf/test_rays.py#L115
    - https://github.com/kornia/kornia/blob/ce434e467faf617604bb3383cf78cd0b79f59dbd/tests/nerf/test_rays.py#L140
    - https://github.com/kornia/kornia/blob/ce434e467faf617604bb3383cf78cd0b79f59dbd/tests/nerf/test_data_utils.py#L14
    - https://github.com/kornia/kornia/blob/ce434e467faf617604bb3383cf78cd0b79f59dbd/tests/nerf/test_data_utils.py#L24
              