Update fft solvers for heffte 2.2.0
In heffte v 2.2.0 several options are changed and some backward compatibility is broken. In this issue/MR we change our FFT based solvers in order to account for this.
In heffte v 2.2.0 several options are changed and some backward compatibility is broken. In this issue/MR we change our FFT based solvers in order to account for this.