retrieve prebuild phase diagrams from OpenData (#961)

* retrieve prebuild phase diagrams from OpenData

* try fixing some tests

* fix field typo in test

revert testing against preview

dummy mistake

use request headers

tests: use first available field if primary key n/a

add description for include_gnome

nested fields are not invalid

fix total for progress bar by counting deprecated docs (#957)

* docstring fix

* raise RestError on 400

* fix total by also counting deprecated docs

* ruff

fix electrode test

fix suffix for root level endpoints