Fix inverted player input when in a vehicle

Fixes #969

Author: kennytv

common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_2to1_21/rewriter/EntityPacketRewriter1_21_2.java

@@ -291,15 +291,15 @@ public void register() {
 
             byte updatedFlags = 0;
             if (forward > 0) {
-                updatedFlags |= 1;
+                updatedFlags |= 1; // Forward
             } else if (forward < 0) {
-                updatedFlags |= 1 << 1;
+                updatedFlags |= 1 << 1; // Backward
             }
 
-            if (sideways < 0) {
-                updatedFlags |= 1 << 2;
-            } else if (sideways > 0) {
-                updatedFlags |= 1 << 3;
+            if (sideways > 0) {
+                updatedFlags |= 1 << 2; // Left
+            } else if (sideways < 0) {
+                updatedFlags |= 1 << 3; // Right
             }
 
             if ((flags & 1) != 0) { // Jumping