Review/Redefine BDC Role

We should review and redefine the BDC role and sync those responsibilities across the team.

We should also have an automated way to rotate the BDC to make it easier to route Slack questions to the right person. (Per has already started on this)

A/C:

 - Current BDC role reviewed
 - Identify problems with current BDC and how it's been done
 - Write a doc with alternatives
 - Doc reviewed and agreed on with team
 - Issues put into the refinement backlog

Current doc:  https://docs.google.com/document/d/1_hM-krlhCPI-ZcpRqY9u1N6Y1vgCDRNbJdtm39SYiYQ/edit