Allow for unresolved states to be a graph rather than a flow.

Once you start extending unresolved states switching between them becomes painful because it is rare that you are still modelling a progression along a single flow and instead you are more likely modeling a graph of potential status.

It would be great if the nextState property of the configuration supported an `array` so that we could better represent the graph of status options and make it easier to use.

To quote @beaulebens:

> So from a user’s perspective, if you had one of these fancy things configured, then from the current status “X”, there might be 3 possible “next statuses” — A, B, C. If you clicked the button (which would have the label of the current status, X), then a drop-down would appear and you’d pick from A/B/C, whereupon the status (and label) would change to… let’s say B. From there, if you clicked it again, you’d get a new drop-down with whatever the “next statuses” from B might be (G, H, I). So rather than just cycling through a loop of statuses, it’s a bit more pick-your-own-adventure.

Start by locating the configuration that defines nextState and the UI handling unresolved statuses. Trace how a single next state is displayed and advanced, then determine where an array of possible states can be selected. Done means unresolved statuses can expose multiple next states, present them as choices, and transition to the selected status.

Written by the indexing model from the issue text.