Implements some micro-optimizations

PkmnLib.Static/Species/Form.cs

@@ -88,7 +88,7 @@ public interface IForm : INamedValue
     /// <summary>
     /// Check if the form has a specific flag set.
     /// </summary>
-    bool HasFlag(string key);
+    bool HasFlag(StringKey key);
 
     /// <summary>
     /// Check if the form is a battle-only form, meaning it should return to its original form after the battle ends.
@@ -208,7 +208,7 @@ public class FormImpl : IForm
     public StringKey GetRandomHiddenAbility(IRandom rand) => HiddenAbilities[rand.GetInt(HiddenAbilities.Count)];
 
     /// <inheritdoc />
-    public bool HasFlag(string key) => Flags.Contains(key);
+    public bool HasFlag(StringKey key) => Flags.Contains(key);
 
     /// <inheritdoc />
     public bool IsBattleOnlyForm { get; }