Fix: force flag update for session players entity flags (#5810)

* Force flag update for session player when living entity flag update.

* Requested changes.

* Removed useless import.

core/src/main/java/org/geysermc/geyser/entity/type/player/SessionPlayerEntity.java

@@ -397,6 +397,17 @@ public class SessionPlayerEntity extends PlayerEntity {
         super.setAbsorptionHearts(entityMetadata);
     }
 
+    @Override
+    public void setLivingEntityFlags(ByteEntityMetadata entityMetadata) {
+        super.setLivingEntityFlags(entityMetadata);
+
+        // Forcefully update flags since we're not tracking thing like using item properly.
+        // For eg: when player start using item client-sided (and the USING_ITEM flag is false on geyser side)
+        // If the server disagree with the player using item state, it will send a metadata set USING_ITEM flag to false
+        // But since it never got set to true, nothing changed, causing the client to not receive the USING_ITEM flag they're supposed to.
+        this.forceFlagUpdate();
+    }
+
     @Override
     public void resetMetadata() {
         super.resetMetadata();