ENH: Add 1D FFT Example

[tbirdso]

Takes in mouse liver RF image (public data from ITKUltrasound testing) and performs FFT along scanline.

Also adds option in compare_to_baseline CMake function to optionally allow only Python (no C++) baseline test creation.

Input

Output modulus

Output phase

Closes #354.

[tbirdso]

Fixed reference to input screenshot in .rst documentation.

[tbirdso]

It looks like there is a larger issue of test dependencies here, the log file shows that ComputeFFTInOneDimension baseline comparisons are run before the ComputeFFTInOneDimension test. It appears that test dependencies are being set in CMake as one would expect. Need to dig deeper into this.

[tbirdso]

Note that it also looks like we will need to resolve https://github.com/InsightSoftwareConsortium/ITKSphinxExamples/issues/362 before this one can be merged as 1D FFT classes were added after the 5.2.0 release.