Add unit tests for the Google Books providers

[Pithaya]

Adds unit tests for the Google Books providers and fixes some issues:

• The comic file name format from the docs (Series_Name (SeriesYear) #IssueNum (of Count) (PubYear).ext) was not being matched
• GetSearchResults was not setting the provider id, so picking a search result wasn't working (see: https://github.com/jellyfin/jellyfin/issues/5437)
• Genres / tags were not parsed correctly
• The PersonInfo metadata was not parsed

I used the same test project as #70 to minimize conflicts.

(By the way, it would be nice if this repo could also get the hacktoberfest topic 🙂)