Consolidate numpy sample key files #255
Description
Currently we have numpySample keys spread across different files in this directory https://github.com/openclimatefix/ocf-data-sampler/tree/tensorstore_test/ocf_data_sampler/numpy_sample it would be easier to navigate what keys are available if they are in one file and also could store more information of their shapes there.