Optional Value on ItemData + Extract subject location oid

[glow-mdsol]

• pick out the StudyEnvironmentSiteNumber as an attribute
• move to pytest
• make ItemData value unset'able
• Migrate from setup.py to poetry
• Split CI task to have ci, docs, publish tasks

[isparks]

Reviewed with no comments. Thanks Geoff for continuing to maintain this.

[isparks]

Note I can't merge this because its marked as a work in progress.