Fixes#1494.
* Add import support for `google_logging_organization_sink`, `google_logging_folder_sink`, `google_logging_billing_account_sink`.
Using `StateFunc` over `DiffSuppressFunc` should only affect tests; for some reason `TestAccLoggingFolderSink_folderAcceptsFullFolderPath` expected a `folder` value of `folders/{{id}}` vs expecting `{{id}}` when only `DiffSuppressFunc` was used, when in real use `DiffSuppressFunc` should be sufficient.