Change Basket to Postgres

[glogiotatidis]

We currently have a MariaDB database only used by Basket. We want to move this to the existing PostgreSQL database used by other projects.

Steps

• [ ] Ping OMN team to not use the Admin during the migration window
• [ ] Create DB + users for prod / stage / dev on current Postgres
• [ ] copy database
• [ ] Re-deploy Basket with new DB settings.