Support for Gatsby Cloud SSR / DSG jobs to have constant IP addresses so data sourcing from them can be IP whitelisted

Enterprise Gatsby Cloud allows for site builds to run on a cluster with dedicated IPs, however SSR / DSG jobs do not have the same ability. For uses cases where data is needing to be sourced from private, restricted APIs, the inability to whitelist IPs of SSR / DSG pods effectively means those rendering modes cannot be used. Which severely limits how Gatsby can be used.