Add new provider: Eni

[MacFJA]

Add ENI.

• No public API.
• Web-scraping is possible (2 steps: search, results consulting)

Available information:

• Title
• Sub-title
• Table of content
• Author(s)
• Author(s) bio
• Description
• Publication date
• Genre
• Internal identifier
• ISBN (13)
• Format
• Page count
• Difficulty