By Christoph Steitz and Victoria Waldersee FRANKFURT (Reuters) -German utility Uniper on Monday became the latest firm to write down its financial exposure to the suspended Nord Stream 2 pipeline project and unveiled a sales process for its Russian subsidiary in response to Moscow’s invasion of Ukraine. Berlin has halted the Nord Stream 2 Baltic Sea pipeline project, which would have doubled Russian gas flows to Germany, following Russia’s invasion of Ukraine, which Moscow calls a “special operation”. Uniper said it would fully impair its 987 million euro ($1.07 billion) loan to Nord Stream 2,…