Display clean up window after database refresh is complete.

If the Version Handler's clean up files window is shown before asset
database refresh is complete, the window can end up in a state where
it's not redrawn correctly and doesn't function.  This change
makes sure the window is only shown when asset database refresh and
compilation is complete.

Bug: 150886091
Change-Id: Ic9b3fa53b488159443162834bf20f8a045c3c4f8

Author: Stewart Miles

source/VersionHandlerImpl/src/VersionHandlerImpl.cs

@@ -2123,7 +2123,7 @@ public static void UpdateVersionedAssets(bool forceUpdate, Action complete) {
             }
         }
 
-        if (cleanupFiles.Count > 0) {
+        if (cleanupFiles.Count > 0 && !Refreshing) {
             var window = MultiSelectWindow.CreateMultiSelectWindow(PLUGIN_NAME);
             Action<string> logObsoleteFile = (filename) => {
                 Log("Leaving obsolete file: " + filename, verbose: true);