Extracted some pages to their own assembly and finished the artifact display page code

OpenArchival.Blazor.FileViewer/IFileViewer.cs

@@ -0,0 +1,18 @@
+using Microsoft.AspNetCore.Components;
+using MudBlazor;
+using OpenArchival.DataAccess;
+
+namespace OpenArchival.Blazor.FileViewer;
+
+public interface IFileViewer
+{
+    /// <summary>
+    /// The file to be displayed by the viewer component
+    /// </summary>
+    public FilePathListing File { get; set; }
+    
+    /// <summary>
+    /// To be called when the file viewer has determined how tall its content is so that the containing carousel can resize
+    /// </summary>
+    public EventCallback<int> OnHeightMeasured { get; set; }
+}