Potential CT block

[ml-evs]

Quick note from discussion with @elbee99, a CT block could be nice. Seems to be vague consensus around imaging formats that look like stacks of TIFFs, so would just need some code to make a nice 3D viewer. Only other wrinkle is that these things can be quite large (up to 10 GB) which wouldn't work out of the box -- we can think about different ways of streaming files for this use case (e.g., Globus, or just more advanced chunking than we are doing atm), but this may ned to wait until block parsing is done asynchronously (c.f. #364).