Use environment variables when applying migration

[dankolbman]

Migrations are automatically applied in the dockerfile using the below command: https://github.com/overture-stack/ego/blob/19d31d47464d76c9cf5eb9e205678afaef4d6ab4/Dockerfile#L34

This line makes assumptions about the database despite the database connection being configurable through environment variables. It should be adjusted to use EGO_DB_HOST, EGO_DB_PORT, EGO_DB, EGO_DB_USER, and EGO_DB_PASS variables from the environment to allow migrating a database at any address