[java] armor stand comparator detection

A system of detecting if armor is on an armor stand using Redstone should be in place. This would allow for greater creativity in redstone builds by allowing for the player to sort stands, auto armor stand swappers, and more.

There is currently no system to do this in the current game, due to the inability to use command blocks in a survival game

Detection could be done by testing the block the armor stand is on, or the blocks beside it.