Add 'folders' attribute to Cloud data source

[psmolkin]

Duplicate reverted https://github.com/yandex-cloud/terraform-provider-yandex/pull/207 see issue https://github.com/yandex-cloud/terraform-provider-yandex/issues/239

Additional yandex_resourcemanager_cloud data source attribute

 folders = [
   {
     folder_id = "06nur34....."
     name      = "some_name"
   },
   {
     folder_id = "8a8i9ag....."
     name      = "some_name2"
   },