Add support for adventage, disadventage and emphasis rolls.

composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/parser/arithmetic/Instruction.kt

@@ -18,7 +18,14 @@ sealed class Instruction(
         }
 
         override fun toString(): String {
-            return "${sign.sign}${quantity}d${faces}"
+            return "${sign.sign}${
+                when (modifier) {
+                    Modifier.ADVANTAGE -> "a"
+                    Modifier.DISADVANTAGE -> "d"
+                    Modifier.EMPHASIS -> "e"
+                    null -> ""
+                }
+            }${quantity}d${faces}"
         }
     }