Improve the modularization of the project

[bchapuis]

I think we should continue our effor to improve the modularization of baremaps.

Here are some of the codecs we could extract from the core and put in dedicated modules.

• baremaps-shapefile: a standalone shapefile reader
• baremaps-flatgeobuf: a standalone flatgeobuf reader and writer
• baremaps-mbtiles: a standalone mbtiles reader and writer

Some other parts of the code may also benefit from being put in modules but the advantage is less clear.

• baremaps-workflow: a workflow engine (the implementation of the tasks should probably remain in core)
• baremaps-iploc: the utilities to perform ip to location based on ripe/nic/rir/nro data (I still struggle with the name of this module)
• baremaps-geocoder: the utilities for creating a geocoder based on lucene.
• etc.

What are you thought on this plan? I intent to use this issue to track the progress on these changes. They will be implemented with multiple small pull requests and the list of modules will evolve.