Add wikidata field for authors

[ccamara]

This PR simply creates a field for wikidata and displays it on the author's profile. Nothing else.

Adding a wikidata field to author's profile would be the first step to address the issues with multiple, multilingual wikipedia links #1585

[ccamara]

This PR simply creates a field for wikidata and displays it on the author's profile. Nothing else.

Currently, any string can be added to the field. I would want to add the following:

• validation, i.e. to only accept Q followed by a number
• automatic removal of https://wikidata.org
• Some description/label explaining what is expected to be inputted/or how to get the wikidata's ID

But I do not know how to do it. Suggestions are welcome.

Also, I would like to create an importer, but this will come in future PR, if I manage to understand how the inventaire import works (I believe there will be quite some things to re-use).

[mouse-reeve]

I believe the only change needed her is removing the change to the model. Otherwise it's a great addition to have this be an editable field on Author.

[mouse-reeve]

You don't need to add this here -- the field is already on this model, it's inherited from the parent model, BookDataModel: https://github.com/bookwyrm-social/bookwyrm/blob/main/bookwyrm/models/book.py#L55

[ccamara]

thanks for dealing wiht this, @mouse-reeve . Apologies because life got busy for me and I left that unfinished. Glad you did it!