By Simon Johnson and Anne Kauranen STOCKHOLM (Reuters) -Finland and Sweden voiced optimism on Tuesday that common ground can be found with Turkey over its objections to them joining NATO amid a flurry of diplomatic activity aimed at smoothing their path into the 30-nation alliance. Turkey surprised many NATO allies on Monday by saying it would not support membership for Sweden and Finland after the two countries took the widely anticipated step of agreeing to apply to join the U.S.-led alliance this week. “Statements from Turkey have very quickly changed and become harder during the last few d…