Add vald to atom data (#380)

* Add VALD data parser

* changename and fix ion_charge

* clean up unusued params

* add vald tests

* add vald to output, as well as helper functions to create atomic line list

* fix test by not stripping molecules

* change for loop to list comprehension

* improve documetation

* further improve docstring coverage

* further small docstring improvements

* apply sourcery

* add js and Es to linelist

* change vald_linelist to generic linelist

* add test for stripping moleculess

* add test for linelists

* handle case of linelist requested when not stripping molecules

* test linelist when not stripping molecules

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Co-authored-by: Aarya Chaumal <aarya.chaumal@gmail.com>