Consular relations — Immunity — Consular officials — Immunity from civil proceedings — Nature and scope of immunity — Vienna Convention on Consular Relations, 1963, Articles 5 and 43 — Immunity limited to “acts performed in the exercise of consular functions” — Providing overnight accommodation for national of sending State in consular offices — Whether consular function — Consular function performed in unlawful manner — Whether affecting immunity from jurisdiction — The law of the United States