Add cycif tonsil image and move spatialomics to imaging

[jmuhlich]

This adds a new cyclic immunofluorescence image dataset into a new imaging directory and renames/reorganizes the existing spatialomics directory into imaging. This renaming was done with the approval of @FloWuenne who originally added the spatialomics data. We decided the data there was all applicable to image processing in general and thus "imaging" would be a better name. READMEs have been added to the leaf directories with more detailed info on each file collection.

[nvnieuwk]

LGTM! Can you also open a quick PR that updates the tests/config/test_data.config file in the modules repo so we don't break any tests for modules dependent on the spatialomics data? :)

(Also please wait for a second approval since this is a new category 😁)

[ewels]

LGTM, thanks for this!