Metamask DLL should only be available on webGL (#1074)

Fixing metamask processing so that we don't ever get the iOS build error.

src/UnitySampleProject/Assets/Scripts/Editor/DllPlatformFixing.cs

@@ -0,0 +1,32 @@
+using UnityEditor;
+
+public class DllPlatformFixing : AssetPostprocessor
+{
+    private static void OnPostprocessAllAssets(string[] importedAssets, string[] deletedAssets, string[] movedAssets,
+        string[] movedFromAssetPaths)
+    {
+        for (var i = 0; i < importedAssets.Length; i++)
+            if (importedAssets[i].Contains("ChainSafe.Gaming.Unity.MetaMask"))
+            {
+                var importer = (PluginImporter)AssetImporter.GetAtPath(importedAssets[i]);
+                if (importer == null) continue;
+                //If it's already set to false, that means we've been here and can early return.
+                if(!importer.GetCompatibleWithAnyPlatform())
+                    return;
+
+                importer.SetCompatibleWithAnyPlatform(false);
+                importer.SetCompatibleWithPlatform(BuildTarget.WebGL, true);
+                importer.SetCompatibleWithPlatform(BuildTarget.iOS, false);
+                importer.SetCompatibleWithPlatform(BuildTarget.Android, false);
+                importer.SetCompatibleWithPlatform(BuildTarget.StandaloneWindows, false);
+                importer.SetCompatibleWithPlatform(BuildTarget.StandaloneOSX, false);
+                importer.SetCompatibleWithPlatform(BuildTarget.StandaloneLinux64, false);
+                importer.SetCompatibleWithPlatform(BuildTarget.StandaloneWindows64, false);
+                importer.SetCompatibleWithEditor(false);
+
+
+                EditorUtility.SetDirty(importer);
+                importer.SaveAndReimport();
+            }
+    }
+}