Standardize and refactor our form + network request state

[taggartbg]

Follow-up from this PR conversation between @liamzebedee and @taggartbg

All of our network calls (or any async side effects with success and failure return events) are being handled as individual cases, meaning we have a lot of repeated boilerplate and inconsistencies in how they're handled. Our refactoring should implement something at the saga level to allow a standardized way to call other actions or update state. (NB: routines seems like a good pattern here, with (trigger, success, failure, fulfilled) states)

Our refactor here should also account for the way our forms trigger and respond to these routines. From @liamzebedee - form flow: reframing the flow as something declarative would work well, ie. form step / current page, and then substep if we need it. In this way, we can persist and rehydrate and the form would still be there. And maybe a continue button which navigates to the current form step page.

• Plan async side effect handling
• Plan declarative forms
• Implement solutions