The borough engineer in Lansdale has been tapped to inspect the Center for the Performing Arts in the wake of allegations about fire code violations there.   Code Enforcement Director John Ernst Wednesday night told Borough Council that it appears a use and occupancy permit was issued in spite of the violations with the intention of fixing the safety issues during the next series of rennovations at the 19th century building on West Main Street.   That second phase of construction never happened and some borough officials are saying it is clear that the building should not have been allowed to open.   The borough engineer will be paid about $14,000 to inspect the Performing Arts center.