Linked Series (#1230)

* Implemented the ability to link different series together through Edit Series. CSS pending.

* Fixed up the css for related cards to show the relation

* Working on making all tabs in edit seris modal save in one go. Taking a break.

* Some fixes for Robbie to help with styling on

* Linked series pill, center library

* Centering library detail and related pill spacing

- Library detail cards are now centered if total number of items is > 6 or if mobile.
- Added ability to determine if mobile (viewport width <= 480px
- Fixed related card spacing
- Fixed related card pill spacing

* Updating relation form spacing

* Fixed a bug in card detail layout when there is no pagination, we create one in a way that all items render at once.

* Only auto-close side nav on phones, not tablets

* Fixed a bug where we had flipped state on sideNavCollapsed$

* Cleaned up some misleading comments

* Implemented RBS back in and now  if you have a relationship besides prequel/sequel, the target series will show a link back to it's parent.

* Added Parentto pipe

* Missed a relationship type

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

API/Entities/Metadata/SeriesRelation.cs

@@ -0,0 +1,25 @@
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations.Schema;
+using API.Entities.Enums;
+
+namespace API.Entities.Metadata;
+
+/// <summary>
+/// A relation flows between one series and another.
+/// Series ---kind---> target
+/// </summary>
+public class SeriesRelation
+{
+    public int Id { get; set; }
+    public RelationKind RelationKind { get; set; }
+
+    public virtual Series TargetSeries { get; set; }
+    /// <summary>
+    /// A is Sequel to B. In this example, TargetSeries is A. B will hold the foreign key.
+    /// </summary>
+    public int TargetSeriesId { get; set; }
+
+    // Relationships
+    public virtual Series Series { get; set; }
+    public int SeriesId { get; set; }
+}