db: Prevent frontend from starting if codeintel-db == frontend db
Created by: efritz
We require distinct database instances (either different hosts, or a different database on the same host) for the frontend db and the codeintel db. Our docs describe this behavior already, but I forgot to actually add the check here.
Not sure if a panic is appropriate over a log and an os.Exit, and I will very very happily take suggestions for error text.