assert_lacc_equals_i_am_accel_node mandatory argument

Please make i_am_accel_node a mandatory argument to assert_lacc_equals_i_am_accel_node. Otherwise it breaks the original purpose of this assert test.

https://gitlab.dkrz.de/icon-libraries/libfortran-support/-/blob/master/src/mo_fortran_tools.F90?ref_type=heads#L2352