Make the client validate character information (#3563)

Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>

Content.Shared/Preferences/ICharacterProfile.cs

@@ -5,7 +5,14 @@ namespace Content.Shared.Preferences
     public interface ICharacterProfile
     {
         string Name { get; }
+
         ICharacterAppearance CharacterAppearance { get; }
+
         bool MemberwiseEquals(ICharacterProfile other);
+
+        /// <summary>
+        ///     Makes this profile valid so there's no bad data like negative ages.
+        /// </summary>
+        void EnsureValid();
     }
 }