Banking giant UBS is ramping up its threats to leave Switzerland and set up shop in the US — a radical response to Swiss regulators who have proposed onerous new capital requirements on the financial behemoth, The Post has learned.Executives at the 162-year-old Swiss bank — led by highly regarded Chairman Colm Kelleher and CEO Sergio Ermotti — have even recently met with Trump administration officials to prepare for the possible seismic strategy shift that could include the purchase of a US bank or a merger ...