Display and compare image sets function

[mperrin]

Notes on the fly from a discussion with @kglidic and @AarynnCarter based on @kglidic's display_medsub_images

What is the specific use case? Marshall asserts, it's comparing before and after for a given image processing step, to assess whether the image processing step is doing what the user intends.

• great to have a function that displays interactively before-and-after image pairs for image processing steps
• Kayli will work to generalize. Can put into a function in spaceklip plotting or utils, etc.
• can we restructure it to take a database object as an input? Versus giving it a before and after directory name.
  • Passing in directory names is more robust to Notebook cells being run out of order.
  • Get root directory from the database, pass in subdirectories as strings (consistent with how they are passed to the various image tools functions)

Additional possible similar display function cases for other steps such as the image registration and alignment.