External Read only DB for Observer

When deploying the DB on cluster it is possible to have Read Only replicate DB too.

Adding value for data consumption by third-party systems such as Phoenix API, data warehousing, business intelligence reporting and customer's system will be enhanced if Observer allows for two database endpoints: one for the original system and the other for other services querying the database.

I suggest to have the ability to set 2 endpoints on Observer and configure the Phoenix API to RO instance.