Zotero READ connector

Thanks to @emichelet , work has begun on the Zotero (READ) connector, here: https://gitlab.huma-num.fr/datasphere/heimdall/connectors/zotero .
We just laid the groundwork for now, we'll see in a few weeks where this leads us to.

Useful intel regarding Zotero's API:

• https://www.zotero.org/support/dev/web_api/v3/start
• https://www.zotero.org/support/dev/web_api/v3/basics
• https://gist.github.com/dstillman/6eeace93a5c29775d39c