More test cases for FOURIER formula

This adds test cases for N(data length) for non powers of 2.
This tests real and complex input cases. It also tests polar and
non-polar output case. The reference(expected) numbers were obtained
using fft() of Matlab R2018b. Finally the inverse transform is
compared is compared with original inputs for correctness.

Change-Id: Ibc13fb5ce900facd3fb0896e85a4e0d1694ad7f3
Reviewed-on: https://gerrit.libreoffice.org/68640
Tested-by: Jenkins
Reviewed-by: Dennis Francis <dennis.francis@collabora.com>