Draft: Add simple assembler and manual geometry devices using extra_geom

Copied over from my hacky utils; have used these in my development Karabo environment for a while. Devices here (and corresponding changes to manager) sketch how I interpret our plan for the next step in online calibration topology: manual geometry devices to be later supplanted by or supplemented with something using encoders or such.

The heavy lifting (defining what a geometry is assembling image) mostly left to extra_geom (need to update dependencies). And the assembler is mostly a TrainMatcher which calls position_modules_fast on _send.

Would propose to move implementation of Manual[Detector]Geometry into [Detector]Correction.py to tidy up a bit.