MILAN/FRANKFURT, March 16 (Reuters) - UniCredit made a low-ball unsolicited bid for Commerzbank on Monday to pressure it into merger talks and unlock an 18-month stalemate over what would be one of ‌the biggest European cross-border banking deals since the 2008 financial crisis. The Italian bank does not expect ‌its offer, worth around 35 billion euros ($40 billion), to convince many shareholders. But the move ratchets up the pressure and gives UniCredit, which ​already owns nearly 30% of Frankfurt-based ...