Sovereign immunity — Foreign States — Enforcement of arbitral award against foreign State — Proceedings for obtaining an exequatur and attachment of assets of foreign State — Whether entitled to jurisdictional immunity or immunity from execution — Waiver — Whether insertion of arbitration clause in original contract constitutes waiver of jurisdictional immunity for proceedings instituted to obtain an exequatur for arbitral award — Whether waiver of jurisdictional immunity implies waiver of immunity from execution — Whether proceedings to obtain an exequatur for award violate a foreign State's immunity from execution — The law of France