Adding pod-cpu-hog experiment in litmus-python

DoD:

- Follow the contribute guide to generate an experiment that is, by default, pod-cpu-hog with the name sample_exec_chaos.

- Use sample guide [contribute/developer-guide](https://github.com/litmuschaos/litmus-python/tree/master/contribute/developer-guide)
or [create-chaos-experiments-using-the-litmuschaos-python-sdk](https://dev.to/oumkale/create-chaos-experiments-using-the-litmuschaos-python-sdk-4492) to generate the experiment and test it.

- Replace all occurrences of sample_exec_chaos with pod-cpu-hog and sample_category with generic.

- Test the experiment both locally and using the operator or [okteto](https://github.com/litmuschaos/litmus-python/tree/master/contribute/developer-guide#steps-to-test-experiment) approach.

- Once tested, raise a PR in the litmus-python repo for pod-cpu-hog.

- [Optional] [Contributing Guidelines for the Chaos Hub](https://github.com/litmuschaos/community-charts/blob/master/CONTRIBUTING.md)

Note: The LitmusChaos SDK is a development kit that generates experiment. Follow the guidelines in this [blog](https://dev.to/oumkale/create-chaos-experiments-using-the-litmuschaos-python-sdk-4492)
to create and test your experiment. Once it is working, replace the default sample experiment name with pod-cpu-hog, as the default generated experiment is pod-cpu-hog.

Start with contribute/developer-guide and the linked LitmusChaos Python SDK guide to generate the experiment. Test the generated pod-cpu-hog experiment locally and through the operator or Okteto workflow described in the guide; done means the generated experiment works and a pull request is ready in litmus-python.

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