Refresh jwt using dcplib.

[DailyDreaming]

We already refresh tokens (#446), so I view this as fairly low priority, but we could leverage:

https://github.com/HumanCellAtlas/dcplib/blob/5704ea9bc8c07f6ac7905cb63f45e34f3fd4213d/dcplib/security/dcp_service_account.py#L10

And centralize how we refresh jwt.