feat: Add GraphQLConvertable

Add trait which allows enums to be converted to the GQL values.

src/Definition/Concerns/GraphQLConvertable.php

@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Worksome\GraphQLHelpers\Definition\Concerns;
+
+use Jawira\CaseConverter\Convert;
+
+/**
+ * @property-read string $name
+ */
+trait GraphQLConvertable
+{
+    public function graphQLValue(): string
+    {
+        return (new Convert($this->name))->toMacro();
+    }
+}