Fix Syntax Error: Expected Name found :

There was a bug with the enum placeholder ordering

Input like the following
```
            interface SomeInterface  {
                product_type: String @doc(description: "The type of product, such as simple, configurable, etc.")
            }
            enum SomeEnum {
            }
```

would have placeholder logic ran against it and end up like
```
            interface SomeInterface  {
                product_type: String @doc(description: "The type of product, such as simple, configurable, etc.")
            }
            enum SomeEnum {
placeholder_graphql_field: String
}
```

This caused an error, something in the AST was trying to make it resolve against the word "Type" in the @doc description

By fixing the enum so that it does not have `: String` in it the AST is generated successfully, we do this by replacing those empty enums first so that they cannot get caught by the empty type check

Author: convenient

lib/internal/Magento/Framework/GraphQlSchemaStitching/GraphQlReader.php

@@ -337,19 +337,24 @@ private function addPlaceHolderInSchema(string $graphQlSchemaContent) :string
         $typeDefinitionPattern = '([^\{]*)(\{[\s\t\n\r^\}]*\})';
         $spacePattern = '([\s\t\n\r]+)';
 
-        //add placeholder in empty types
+        // TODO review this workaround
+        // Replace enums before types, there is a bug in which some enums are caught by the type regex
+        // If we process them first they will have their placeholder inserted appropriately without the :String suffix
+        // This means they will not be caught by the following preg_replace
+        //add placeholder in empty enums
         $graphQlSchemaContent = preg_replace(
-            "/{$typesKindsPattern}{$spacePattern}{$typeNamePattern}{$spacePattern}{$typeDefinitionPattern}/im",
-            "\$1\$2\$3\$4\$5{\n{$placeholderField}: String\n}",
+            "/{$enumKindsPattern}{$spacePattern}{$typeNamePattern}{$spacePattern}{$typeDefinitionPattern}/im",
+            "\$1\$2\$3\$4\$5{\n{$placeholderField}\n}",
             $graphQlSchemaContent
         );
 
-        //add placeholder in empty enums
+        //add placeholder in empty types
         $graphQlSchemaContent = preg_replace(
-            "/{$enumKindsPattern}{$spacePattern}{$typeNamePattern}{$spacePattern}{$typeDefinitionPattern}/im",
-            "\$1\$2\$3\$4\$5{\n{$placeholderField}\n}",
+            "/{$typesKindsPattern}{$spacePattern}{$typeNamePattern}{$spacePattern}{$typeDefinitionPattern}/im",
+            "\$1\$2\$3\$4\$5{\n{$placeholderField}: String\n}",
             $graphQlSchemaContent
         );
+
         return $graphQlSchemaContent;
     }