feat: rename potion_level placeholder

Last edit, I promise 😬

src/main/java/com/extendedclip/papi/expansion/player/PlayerExpansion.java

@@ -448,6 +448,23 @@ public final class PlayerExpansion extends PlaceholderExpansion implements Confi
             case "is_inside_vehicle":
                 return bool(p.isInsideVehicle());
         }
+
+        if (identifier.startsWith("has_potion_effect_")) {
+            final PotionEffectType potion = PotionEffectType.getByName(identifier.replace("has_potion_effect_", ""));
+            return bool(potion != null && p.hasPotionEffect(potion));
+        }
+
+        if (identifier.startsWith("potion_effect_level_")) {
+            final PotionEffectType potion = PotionEffectType.getByName(identifier.replace("potion_effect_level_", ""));
+
+            if (potion == null || !p.hasPotionEffect(potion)) {
+                return "0";
+            }
+
+            //noinspection DataFlowIssue
+            return String.valueOf(p.getPotionEffect(potion).getAmplifier());
+        }
+
         // return null for unknown placeholders
         return null;
     }