Move whiskermenu settings into the xfconf panel file (MR 10)

In xfce4-whiskermenu-plugin 2.8.0 the storage location for the menu settings
was moved to xfconf. They are now part of the xfconf file of the panel.

Additionally, the default positioning of the menu elements were changed.

This commit restores the whiskermenu layout as they were before in
postmarketOS Xfce4.

config/xfce4/panel/whiskermenu-1.rc

-button-icon=/usr/share/pixmaps/postmarketos-logo.svg
-item-icon-size=2
-view-mode=1
-position-search-alternate=false
-position-categories-alternate=false
-menu-width=400

config/xfce4/xfconf/xfce-perchannel-xml/xfce4-panel.xml

@@ -41,7 +41,12 @@
     </property>
   </property>
   <property name="plugins" type="empty">
-    <property name="plugin-1" type="string" value="whiskermenu"/>
+    <property name="plugin-1" type="string" value="whiskermenu">
+      <property name="button-icon" type="string" value="/usr/share/pixmaps/postmarketos-logo.svg"/>
+      <property name="position-search-alternate" type="bool" value="true"/>
+      <property name="position-profile-alternate" type="bool" value="true"/>
+      <property name="menu-width" type="int" value="400"/>
+    </property>
     <property name="plugin-2" type="string" value="tasklist"/>
     <property name="plugin-3" type="string" value="separator">
       <property name="expand" type="bool" value="true"/>