optimize song artwork scanning (#527)

ErsatzTV.Infrastructure/Migrations/20211203191336_Add_ArtworkSourcePath.cs

@@ -0,0 +1,25 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ErsatzTV.Infrastructure.Migrations
+{
+    public partial class Add_ArtworkSourcePath : Migration
+    {
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<string>(
+                name: "SourcePath",
+                table: "Artwork",
+                type: "TEXT",
+                nullable: true);
+        }
+
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "SourcePath",
+                table: "Artwork");
+        }
+    }
+}

ErsatzTV.Infrastructure/Migrations/TvContextModelSnapshot.cs

@@ -186,6 +186,9 @@ namespace ErsatzTV.Infrastructure.Migrations
                     b.Property<int?>("SongMetadataId")
                         .HasColumnType("INTEGER");
 
+                    b.Property<string>("SourcePath")
+                        .HasColumnType("TEXT");
+
                     b.HasKey("Id");
 
                     b.HasIndex("ArtistMetadataId");