Rename plugins to libs and update all file references

libs/stripe-php/lib/SingletonApiResource.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace Stripe;
+
+/**
+ * Class SingletonApiResource.
+ */
+abstract class SingletonApiResource extends ApiResource
+{
+    /**
+     * @return string the endpoint associated with this singleton class
+     */
+    public static function classUrl()
+    {
+        // Replace dots with slashes for namespaced resources, e.g. if the object's name is
+        // "foo.bar", then its URL will be "/v1/foo/bar".
+
+        /** @phpstan-ignore-next-line */
+        $base = \str_replace('.', '/', static::OBJECT_NAME);
+
+        return "/v1/{$base}";
+    }
+
+    /**
+     * @return string the endpoint associated with this singleton API resource
+     */
+    public function instanceUrl()
+    {
+        return static::classUrl();
+    }
+}