Integrate restaf / restaflib with CSA

This is a placeholder to track integration of @devaKumaraswamy's excellent [restaf + restaflib](https://github.com/sassoftware/restaf) into CSA, as an enhancement to our own managedRequest API access mechanism.

Looking at the authentication options it should be possible to configure axios with an intereceptor to pause requests while re-authentication happens, and I quite like the idea of moving h54s to axios in general for the next version - it does a lot of things elegantly which we implemented from scratch within h54s (because axios didn't exist at the time).

We need to think about how we best do it - whether to just include restaf here as a branch that we integrate with the login screen and keep the current auth + keepalive mechanisms, or wait until h54s v3 where we can share axios with restaf. Just putting this out there for now.