Implement tool for distributing a KG as BdBags

[cmungall]

The BdBag would contain individual files representing slices of the graph in an agreed upon format (NCATS-Tangerine/translator-knowledge-graph#6). The KG could be slice in any number of ways but a standard way would be by source.

cc @stevencox

[stevencox]

cool.

[cmungall]

not sure if @kltm would have any python code we could reuse here

[kltm]

Direct full bdbags are easy given the python libs as we use them. Slightly more nuanced is the creation of "holey" bdbags and getting the references and hashes sorted out. Code that may be interesting for that would be:

https://github.com/geneontology/go-site/blob/master/scripts/create-bdbag-remote-file-manifest.py

In use like:

sh 'python3 ./scripts/create-bdbag-remote-file-manifest.py -v --walk $WORKSPACE/mnt/$BRANCH_NAME/ --remote http://release.geneontology.org/$START_DATE --output manifest.json'
sh 'mkdir go-release-reference'
sh 'python3 ./mypyenv/bin/bdbag ./go-release-reference --remote-file-manifest manifest.json --archive tgz'

Ideally, that script may be better as a lib or cli to pypi.