Importing books from Amazon - Fill language property when available

### Describe the problem that you'd like solved
When a book is imported (from Amazon in the example given), there is often this note on the edition `Source title: Xxxxxxx (French Edition)` but the language field of this edition is left empty.

### Proposal & Constraints
It seems OL is able to know the language of an edition when importing from at least Amazon. Proposal to fill also the language field.

### Additional context
Example of a German book: https://openlibrary.org/books/OL28278499M/Sch%C3%BClerkunde_auf_Grund_von_Versuchen
Example of a French book: https://openlibrary.org/books/OL28278453M/Kaboul_et_autres_souvenirs_de_la_Troisi%C3%A8me_Guerre_mondiale

### Stakeholders
N/A