FS-7648 add set video on hold, and force preanswer prefix

conf/testing/dialplan/default/0006_set_video_on_hold.xml

+<extension name="video_on_hold">
+  <condition field="destination_number" expression="^99(10[01][0-9])$">
+    <action application="set" data="hold_music=/var/www/vid/notime.mp4"/>
+    <action application="transfer" data="$1"/>  
+  </condition>
+</extension>
+

conf/testing/dialplan/default/0007_pre_answer.xml

+<extension name="pre_answer">
+  <condition field="destination_number" expression="^98(10[01][0-9])$">
+    <action application="pre_answer"/>
+    <action application="transfer" data="$1"/>  
+  </condition>
+</extension>
+