By Max Hunder and Ivan Lyubysh-Kirdey KYIV (Reuters) – As Boris Johnson’s tenure as British Prime Minister hangs by a thread, Ukrainians are hoping the man who some have affectionately taken to calling “Borys Johnsoniuk” can cling on. Johnson is facing a growing rebellion within his own Conservative Party after a slew of ministerial resignations, but Ukrainians fete him as one of their most vocal supporters for overseeing vital supplies of arms and anti-tank weapons to fend off Russia’s invasion. In Kyiv, he has been depicted in street art and is the subject of a portrait exhibition, while a c…