Argentine assets have tumbled so far, so fast that a few stout-hearted investors say it might be time to buy. “Find me a high-yield sovereign country with an IMF program paying so generously,” said Jean-Dominique Butikofer, the Atlanta-based head of emerging-market fixed income at Voya Investment Management, which oversees about $205 billion. “We can agree on the growth outlook, inflation running unexpectedly out of control, the debt dynamic after currency depreciation and worrying technicals. But at…