Run gtk-builder-tool simplify over our ui files

This was done mainly to verify that the tool does not
make any unwarranted changes. The changes included here
are all cosmetic.

gtk/ui/gtkdialog.ui

@@ -5,7 +5,7 @@
     <child type="titlebar">
       <object class="GtkHeaderBar" id="headerbar">
         <property name="show-title-buttons">1</property>
-        <property name="has-subtitle">false</property>
+        <property name="has-subtitle">0</property>
       </object>
     </child>
     <child>

gtk/ui/gtkfilechooserwidget.ui

@@ -165,7 +165,7 @@
                                             <signal name="query-tooltip" handler="file_list_query_tooltip_cb" swapped="no"/>
                                             <signal name="row-activated" handler="list_row_activated" swapped="no"/>
                                             <signal name="cursor-changed" handler="list_cursor_changed" swapped="no"/>
-                                            <signal name="keynav-failed" handler="browse_files_tree_view_keynav_failed_cb" />
+                                            <signal name="keynav-failed" handler="browse_files_tree_view_keynav_failed_cb"/>
                                             <child internal-child="selection">
                                               <object class="GtkTreeSelection" id="treeview-selection2">
                                                 <signal name="changed" handler="list_selection_changed" swapped="no"/>
@@ -445,7 +445,6 @@
     </child>
   </object>
   <object class="GtkPopover" id="rename_file_popover">
-    <property name="position">bottom</property>
     <signal name="closed" handler="rename_file_end"/>
     <child>
       <object class="GtkGrid">

gtk/ui/gtkvideo.ui

@@ -1,3 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
 <interface domain="gtk40">
   <template class="GtkVideo" parent="GtkWidget">
     <child>