[skip ci] Misc stuff (#1766)

* Refactored some code in BookService to make the code easier to understand

* More lint fixes

* Use npm ci for installs in pipeline

* Fixed build system again by deleting nodejs. New build system uses package-lcok going forward.

* Added a test case for Reading Time Estimation calculations

* Some cleanup

* Added even more testing to try and get scare's issue captured.

API/Controllers/DownloadController.cs

@@ -3,7 +3,6 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Threading.Tasks;
-using API.Constants;
 using API.Data;
 using API.DTOs.Downloads;
 using API.Entities;
@@ -12,7 +11,6 @@ using API.Services;
 using API.SignalR;
 using Kavita.Common;
 using Microsoft.AspNetCore.Authorization;
-using Microsoft.AspNetCore.Identity;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.Logging;