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

OpenArchival.Blazor/wwwroot/js/downloadHelper.js

@@ -0,0 +1,12 @@
+function downloadFileFromBytes(fileName, mimeType, bytesBase64) {
+    const link = document.createElement('a');
+    link.href = `data:${mimeType};base64,${bytesBase64}`;
+    link.download = fileName;
+
+    // This is required for Firefox
+    document.body.appendChild(link);
+
+    link.click();
+
+    document.body.removeChild(link);
+}