Remove dependency on ROK when using SDK.

[Techn0logic]

python: 3.8.8
pip: 21.3.1
kubeflow-kale: 0.7.0

Currently running pipeline with -K using SDK fails due to dependency on ROK.

python kale_sdk.py -K
2022-01-20 10:36:54 Kale rokutils:134         [INFO]     Taking a snapshot of the Pod's volumes...
Traceback (most recent call last):
  File "kale_sdk.py", line 136, in <module>
    my_pipeline(parameter="test")
ModuleNotFoundError: No module named 'rok_gw_client'

[Techn0logic]

Also relates to https://github.com/kubeflow-kale/kale/issues/389