Seperate out XCDB and functionality

[reskyner]

• Separate XCDB out into it's own dedicated repo xchem/XCDB
• separate out functions/tools into own dedicated repo xchem/data-tools

The pipeline repo should only include the actual pipeline tasks. i.e. the data-tools and XCDB repos should be released as packages, and their modules/functions called from within the pipeline tasks

This will allow for better control of individual components, and will mean that tests can be written in isolation for functions vs. tasks.