Improvement to extending of expired requests

We've made a change to fix an issue where you weren't able to extend a request that had expired if it contained a check which required an action.

We've also updated how we frame an upcoming expiry date with the label that is used in the side bar. We've changed it from "To be completed by" to "Expired on". This is simpler language and is consistent with how we frame it across other parts of the app.