Boston-based Liberty Mutual Insurance is underway on the construction of its new $325 million, 1.1 million-square-foot regional hub within the nearly $3.2 billion Legacy West development and company officials have released renderings of the soon-to-be Plano campus. The insurance company is one of a number of corporate tenants with projects underway in Legacy West, which has quickly become an epicenter for corporate jobs in North Texas. Upon completion, the Plano regional operations center will…