Fix series and collapsed series progress to be consistent and show average of book series progress

[mikiher]

This fixes #2921.

In a nutshell, the changes are:

• Correct series and collapsed series progress bars to show the same
  • The series card in the Series page and collapsed series book card display the same progress.
  • The progress displayed is now the average of the series books progress (i.e. the sum of all the series individual book progresses, divided by the number of books in the series)
• Added libraryItemIds to collapsedSeries objects return from the server
  • This fixes the bug in seriesIsFinished in LazyBookCard, which currently always returns true
• Simplified progress bar logic in LazyBookCard

[mikiher]

Also added some component tests for LazyBookCard, especially around collapsedSeries cards.

[advplyr]

Great, thanks!