fdo#46102: Fix Java script examples after gbuild'ification

...they contained no class files anymore, due to missing gb_Jar_set_packageroot
calls.  However, those calls only work for subdirectories, i.e., the example
.java files need to be put into a package (I chose
org.libreoffice.example.java_scripts) for all of them).  This in turn required
adaption of the parcel-descriptor.xml files; not sure what the logicalname
entries there are good for if anything -- the macro names at "Tools - Macros -
Run Macro..." now unfortunately(?) contain the fully qualified paths for the
HelloWorld, HighlightText, and MemoryUpdate examples.  There are additional
examples at scripting/examples/java/ that apparently do not get packaged (but I
adapted them anyway).

scripting/examples/java/selector/ScriptSelector.java

@@ -1,3 +1,5 @@
+package org.libreoffice.example.java_scripts;
+
 import javax.swing.*;
 import javax.swing.tree.*;
 import javax.swing.table.*;

scripting/examples/java/selector/parcel-descriptor.xml

@@ -8,7 +8,7 @@
                 Prototype Script Selector GUI for StarOffice
             </description>
         </locale>
-        <functionname value="ScriptSelector.showOrganizer"/>
+        <functionname value="org.libreoffice.example.java_scripts.ScriptSelector.showOrganizer"/>
         <logicalname value="ScriptSelector.showOrganizer"/>
         <languagedepprops>
           <prop name="classpath" value="selector.jar"/>