Pywikibot client to load ISBN related data into Wikidata

Pywikibot script to get ISBN data from a digital library,
and create or amend the related Wikidata item for edition
(with the P212=ISBN number as unique external ID).

Use digital libraries to get ISBN data in JSON format, and integrate the results into Wikidata.

Then the resulting item number can be used e.g. to generate Wikipedia references using template Cite_Q.

Bug: T314942
Change-Id: Ic88ab7125b764e8d296121d7a3d47fb0e53877ab