[flang][NFC] Converted five tests from old lowering to new lowering (part 13) (llvm#179161)

Tests converted from test/Lower:
dummy-argument-assumed-shape-optional.f90,
dummy-argument-contiguous.f90, dummy-argument-optional.f90,
dummy-argument-optional-2.f90, dummy-arguments.f90

Author: eugeneepshteyn