Make Metabase dashboard publicly shareable

[widal001]

Summary

We want to share our Metabase dashboards via a public link so that anyone with the link can view the dashboard, whether or not they have a Metabase account.

Acceptance criteria

• Delivery metrics dashboard can be viewed by anyone who has the the link without logging in
• Sprint metrics dashboard can be viewed by anyone who has the the link without logging in

[mdragon]

Delivery Metrics public link - http://metabase-dev-710651776.us-east-1.elb.amazonaws.com/public/dashboard/e839609f-474e-49fa-b02f-8590b9fe769e
Sprint Metrics public link - http://metabase-dev-710651776.us-east-1.elb.amazonaws.com/public/dashboard/8c13bc6d-6b44-4953-9485-251d8b6d020e

[widal001]

@mdragon helped us get these live in dev!