Roadmap: Move DAT and registration.jl into separate package that depends on DiskArrayEngine

[felixcremer]

We are planning to further separate the loading of the data from the analysis and processing steps.
The way forward is to move the DAT module and the registration.jl code into a separate module which would then depend on DiskArrayEngine and should be able to work on all DiskArrays or DiskArray backed array types.
Then we would be able to process Raster and YAXArray similarly.

This move should also help in making the processing available for other large raster data from other fields such as astronomy or microscopy.

We would still need a good name for the new package.

@meggart