Add "recipients" and "Subject" addresses in the Email table

In the Scheduler Tool we didn't face the scenario of having different email recipients or subjects depending on the Environment, but in the API Readiness app we do.

Right now, there's a condition that checks if the Env is PROD or not to select the proper email addresses to send the Signoff confirmation email to. However, it would be better if we can add a column to avoid that condition and emails hardcoded into the app.