Feature sensitivity analysis step and fix storage optimization

[Bachibouzouk]

Changes proposed in this pull request:

• Function server.run_sensitivity_analysis_step to perform one step of a sensitivity analysis
• Function utils.nested_dict_crawler to return mapping of path within a nested dict to the keys at the lowest nested level
• Enable capacity optimization for storage assets in the epa
• Input timeseries is now not returned to epa in utils.data_parser.py
• Add test class test_utils.TestAccessKPIs to test the nested dict utils functions
• Make the utils function get_nested_valueand set_nested_value raise a Key error with a traceback indicating where in the nested dict this key was missing to help debugging

923 has to be merged prior to merge this PR

The following steps were realized, as well (if applies):

• [ ] Use in-line comments to explain your code
• [ ] Write docstrings to your code (example docstring)
• [ ] For new functionalities: Explain in readthedocs
• [ ] Write test(s) for your new patch of code (pytests, assertion debug messages)
• [x] Update the CHANGELOG.md
• [x] Apply black (black . --exclude docs/)
• [x] Check if benchmark tests pass locally (EXECUTE_TESTS_ON=master pytest)

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