Add No-Intro database export models

SabreTools.Data.Models/NoIntroDatabase/Source.cs

@@ -0,0 +1,19 @@
+using System.Xml;
+using System.Xml.Serialization;
+
+namespace SabreTools.Data.Models.NoIntroDatabase
+{
+    [XmlRoot("source")]
+    public class Source
+    {
+        [Required]
+        [XmlElement("details", typeof(SourceDetails))]
+        public SourceDetails? Details { get; set; }
+
+        [XmlElement("serials", typeof(Serials))]
+        public Serials? Serials { get; set; }
+
+        [XmlElement("file", typeof(File))]
+        public File[]? File { get; set; }
+    }
+}