A better schema for CPF names.

[samueljackson92]

The CPF names are terrible and are based on what they were originally called. It would be good to come up with better names and use this as proposal for standardisation with IAEA

Examples of the CPF values can be found here:

https://mastapp.site/cpf_data.html

They should be:

1. named descriptively,
2. check in the CPF summary that the description and units are useful and meaningful.
3. generate a proposed schema that we can add to the schema in https://github.com/ukaea/ukaea-metadata and to metadata

Documentation for CPF fields:
https://mast-u.gitpages.ccfe.ac.uk/pycpf/cpf/fields/