Case C-710/21, IEF Service: Judgment of the Court (Seventh Chamber) of 16 February 2023 (request for a preliminary ruling from the Oberster Gerichtshof — Austria) — IEF Service GmbH v HB (Reference for a preliminary ruling — Social policy — Protection of employees in the event of the insolvency of their employer — Directive 2008/94/EC — Article 9(1) — Undertaking that has its registered office in one Member State and offers its services in another Member State — Worker whose place of residence is in that other Member State — Work performed in the Member State in which the worker’s employer has its registered office and, one week out of two, in the Member State in which the worker resides — Determining which Member State’s guarantee institution is responsible for meeting outstanding wage claims)