Add SetStates API for use with GetListings request (#31)

Co-authored-by: Leonardo Custodio <leonardo@custodio.me>

Author: SamTheBay

src/Enjin.Platform.Sdk/Enjin.Platform.Sdk.Marketplace/Schema/Queries/GetListings.cs

@@ -67,4 +67,14 @@ public GetListings SetTakeAssetId(MultiTokenIdInput? takeAssetId)
     {
         return SetVariable("takeAssetId", CoreTypes.MultiTokenIdInput, takeAssetId);
     }
+
+    /// <summary>
+    /// Sets the listing states that will be returned.
+    /// </summary>
+    /// <param name="states">The list of states that you want returned</param>
+    /// <returns>This request for chaining.</returns>
+    public GetListings SetStates(params ListingStateEnum[]? states)
+    {
+        return SetVariable("states", CoreTypes.ListingStateEnumArray, states);
+    }
 }

src/Enjin.Platform.Sdk/Enjin.Platform.Sdk/Schema/CoreTypes.cs

@@ -331,4 +331,16 @@ public static class CoreTypes
     /// String for an array of <c>TransferRecipient</c> type.
     /// </summary>
     public const string TransferRecipientArray = "[TransferRecipient!]!";
+
+    // ListingStateEnum
+
+    /// <summary>
+    /// String for <c>ListingStateEnum</c> type.
+    /// </summary>
+    public const string ListingStateEnum = "ListingStateEnum!";
+
+    /// <summary>
+    /// String for an array of <c>ListingStateEnumArray</c> type.
+    /// </summary>
+    public const string ListingStateEnumArray = "[ListingStateEnum!]!";
 }