By Christoph Steitz and Nina Chestney FRANKFURT/LONDON (Reuters) -Russia said it would work out practical arrangements by Thursday for foreign companies to pay for its gas in roubles, raising the probability of supply disruptions as Western nations have so far rejected Moscow’s demand for a currency switch. President Vladimir Putin’s order last week to charge “unfriendly” countries in roubles for Russian gas has boosted the currency after it fell to all-time lows when the West imposed sweeping sanctions against Moscow over its invasion of Ukraine. “No one will supply gas for free, it is simply…