Ingest ExternalReviews from K+

Adds a new entity ExternalChapterMetadata, which would allow us to
extend chapters to Recommendations, Ratings, etc in the future

API/Entities/Metadata/ExternalChapterReview.cs

@@ -0,0 +1,45 @@
+using System.Collections.Generic;
+using API.Entities.Enums;
+using API.Services.Plus;
+
+namespace API.Entities.Metadata;
+
+/// <summary>
+/// Represents an Externally supplied Review for a given Series
+/// </summary>
+public class ExternalChapterReview
+{
+    public int Id { get; set; }
+    public string Tagline { get; set; }
+    public required string Body { get; set; }
+    /// <summary>
+    /// Pure text version of the body
+    /// </summary>
+    public required string BodyJustText { get; set; }
+    /// <summary>
+    /// Raw from the provider. Usually Markdown
+    /// </summary>
+    public string RawBody { get; set; }
+    public required ScrobbleProvider Provider { get; set; }
+    public RatingAuthority Authority { get; set; } = RatingAuthority.User;
+    public string SiteUrl { get; set; }
+    /// <summary>
+    /// Reviewer's username
+    /// </summary>
+    public string Username { get; set; }
+    /// <summary>
+    /// An Optional Rating coming from the Review
+    /// </summary>
+    public int Rating { get; set; } = 0;
+    /// <summary>
+    /// The media's overall Score
+    /// </summary>
+    public int Score { get; set; }
+    public int TotalVotes { get; set; }
+
+    public int ChapterId { get; set; }
+
+    // Relationships
+    public ICollection<ExternalChapterMetadata> ExternalChapterMetadatas { get; set; } = null!;
+
+}