By Jonathan Saul LONDON (Reuters) – A Russian-operated oil tanker that Britain turned away over a week ago has yet to find a port to discharge its cargo, and many other vessels are likely to be in the same position as buyers shun trade deals following Moscow’s invasion of Ukraine. On Tuesday, U.S. President Joe Biden imposed an immediate ban on Russian oil and other energy imports and Britain announced soon after that it would phase out the import of Russian oil and oil products by the end of 2022. The European Union has yet to provide clarity on the prospect of a similar ban by the bloc. The …