Duplicated `getServerSideProps` function and clunky imports / config option retrieval in client

[simeoncarstens]

In app/client/pages/{job,dash,results}.js, there is duplicated code, namely the getServerSideProps function. Furthermore, in #415, I struggled to find a consistent way to retrieve the require_auth option from next.config.js and to import / require firebaseClient and firebaseAdmin only when they are needed.
All of these work, but should be refactored.