* add MNIST DALI example, update README.md

* Fix PEP8 warnings

* reformatted using black

* add mnist_dali to test_examples.py

* Add documentation as docstrings

* add nvidia-pyindex and nvidia-dali-cuda100

* replace nvidia-pyindex with --extra-index-url

* mark mnist_dali test as Linux and GPU only

* adjust CUDA docker and examples.txt, fix import error in test_examples.py

* adjust the GPU check

* Exit when DALI is not available

* remove requirements-examples.txt and DALI pip install

* Refactored example, moved to new logging api, added runtime check for test and dali script

* Patch to reflect the mnist example module

* add req.

* Apply suggestions from code review

* Removed requirement as it breaks CPU install, added note in README to install DALI

* add DALI to Drone

* test examples

* Apply suggestions from code review

* imports

* ABC

* cuda

* cuda

* pip DALI

* Move build into init function

Co-authored-by: SeanNaren <sean@grid.ai>
Co-authored-by: Jirka Borovec <jirka@pytorchlightning.ai>
Co-authored-by: Jirka Borovec <Borda@users.noreply.github.com>
Co-authored-by: Sean Naren <sean.narenthiran@gmail.com>