Scripts/HoO: Templeguardian Anhuur Changes

*Temple Guardian Anhuurs Devine Reckoning will now target a random target instead of his victim
*Also his heroic version of Devine Reckoning will now heal Anhuur
*Reverberating Hymn will now get interrupted when Anhuur takes any damage when the shield of light is gone
*simplyfied the shield counter and damage check
*Implement the achievement 'I hate that Song'.

*possible todo: spell attribe usable_while_stunned may be required also for channeled spells to make the reverberating hymn work properly
because its uneeded here. healthbelowpctdamaged also gets called when the boss gets killed instalty which is pretty ugly when u use  .damage commands for example. and since the damagetaken hook is called on each taken damage there is no need to use another function.