Make filename column resize to text, needed for long package names.

Previously the empty Size & Date columns resize to their headers, and the
Filename column gets squashed. Also made the dialog wide enough.

qrenderdoc/Windows/Dialogs/VirtualFileDialog.ui

@@ -6,7 +6,7 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>594</width>
+    <width>750</width>
     <height>454</height>
    </rect>
   </property>