Documentation improvements

Various documentation improvements (this is an evolving list):

CookBook

• Write MPI and parallel processing
• Mention existing remote modules and add link to the list

Examples

• Finish reviewing examples after migration to sphinx #1865

Tutorials

• Rewrite Segmentation exercises to use all in one app for LSMS, change images...
• Add a 30 minutes introduction with illustrations about SAR images (find Creative Commons support look at SAREDU project for instance https://saredu.dlr.de/)

Build system

• Remove examples tests?
• Remove examples tests baselines?
• Add RunExamples.py script in a new test
• Fix missing example usages
• Improve license header filtering in rst render (itk copyright)
• Handle ApplicationExample
• Move Documentation/Cookbook/Art/ to Data/ after the LFS migration is complete (!387 (merged))