“Kirill S. Serebrennikov … [is] accused of embezzling 133 million rubles, or about $2.3 million, in government funds allocated to a festival he ran. For many in Russia and abroad, however, the case against Mr. Serebrennikov seems like a piece of politically motivated theater: punishment for a provocative artist who has been an outspoken critic of President Vladimir V. Putin. … The Gogol Center, the avant-garde theater he has led since 2012, [is now making a high-profile visit to the German capital].”