fdo#85347 Make file picker modal again

Change-Id: I0e26b9e13e69ed49e7bbbc7f2ac0b04941ee1da7
Reviewed-on: https://gerrit.libreoffice.org/12974Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

fpicker/uiconfig/ui/explorerfiledialog.ui

@@ -8,6 +8,7 @@
     <property name="hexpand">True</property>
     <property name="vexpand">True</property>
     <property name="border_width">6</property>
+    <property name="modal">True</property>
     <property name="type_hint">dialog</property>
     <child internal-child="vbox">
       <object class="GtkBox" id="dialog-vbox1">