Stat Polish (#1775)

* SeriesGroup tag can now have comma separated value to allow a series to be a part of multiple collections.

* Added a missing unit test

* Refactored how collection tags are created to work in the scan loop reliably.

* Added a unit test for RemoveTagsWithoutSeries

* Fixed a bug in reading list title generation to avoid Volume 0 if the underlying file had a title set. Fixed a misconfigured unit test.

* On User stats page, don't show the user selector on reading history, despite if youre an admin. Cleaned up how we show days with 0 reading events to be more clear.

* Refactored the name of a component to reflect what it does

* Removed plugin not using

* Fix an issue where coalescing a key in epub might have multiple html files ending with the key. In this case, let's take the first.

* Added PikaPods to the Readme

* Tried to fix layout shift for charts, but need Robbie's help

* Chart styling

# Added:
- Added: Added styling to force charts into their respective containers.

# Removed:
- Removed: Removed code blocking charts from being visible on mobile.

* Merge conflict

---------

Co-authored-by: Robbie Davis <robbie@therobbiedavis.com>

Kavita.Common/Configuration.cs

@@ -1,6 +1,5 @@
 using System;
 using System.IO;
-using System.Linq;
 using System.Text.Json;
 using Kavita.Common.EnvironmentInfo;
 using Microsoft.Extensions.Hosting;