Create SQL migration scripts

Description

At the moment, I have been adding migration scripts manually to CONTRIBUTING.md for users that are helping out with the project to set up the DB.

Suggested solution

Ideally, we should use a migration script manager like sequelize/ prisma to manage these scripts to create and update databases. Since there isn't a lot of scripts (you can have just 1 script for creating both tables) now, this task should be relatively straight forward for anyone who wants to try out adding either of the above packages to manage the Supabase Postgres table.