Update minecart held block states in 1.17->1.16

Fixes #958

Author: kennytv

common/src/main/java/com/viaversion/viabackwards/protocol/v1_17to1_16_4/rewriter/EntityPacketRewriter1_17.java

@@ -214,6 +214,8 @@ protected void registerRewrites() {
 
         filter().type(EntityTypes1_17.SHULKER).addIndex(17); // TODO Handle attachment pos?
 
+        registerBlockStateHandler(EntityTypes1_17.ABSTRACT_MINECART, 11);
+
         filter().removeIndex(7); // Ticks frozen
     }