Add confirmation page when importing books

[alessandrojean]

Describe your suggested feature

It should let users change entities such as Publisher, Contributor Roles and People to existing entries in the library to avoid creating duplicates when the name saved is different from the one in the external source.

When the user wants to create a new related entity, it should properly label and make it explicit it's a new entry.

Other details

No response

Acknowledgements

• I have searched the existing issues and this is a new ticket, NOT a duplicate or related to another open issue.
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