Update all EF based models to implement new read only interfaces

osu.Game/Database/INamedFileUsage.cs

@@ -0,0 +1,25 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Game.IO;
+
+#nullable enable
+
+namespace osu.Game.Database
+{
+    /// <summary>
+    /// A usage of a file, with a local filename attached.
+    /// </summary>
+    public interface INamedFileUsage
+    {
+        /// <summary>
+        /// The underlying file on disk.
+        /// </summary>
+        IFileInfo File { get; }
+
+        /// <summary>
+        /// The filename for this usage.
+        /// </summary>
+        string Filename { get; }
+    }
+}