FFT Workgroup Ops

[Fletterio]

Description

Adds the option of doing Forward/Inverse FFT on Workgroup-Sized complex data

Testing

On the nahim_complex_tests branch, the example 05 is a bit hacked into shape and the tests were run there. Tested that FFT(IFFT(x)) = x = IFFT(FFT(x))

TODO list:

nahim_complex branch should be merged to master before this one