Simplify state assembly

The runtime has some fairly complex code for assembling state objects between steps in a run. A big part of the complexity comes from merging data objects - although I'm not actually sure we want to do that 🤔

Anyway, one problem of this approach - apart form complexity - is that state objects are default to { data: {}, configuration: {} }. But we shouldn't create those keys unless they're actually needed.

Most of the complexity in this is around unit tests and strict mode. Strict mode ought to be killed off along with this (we can bring it back later), and we just have to go through the tests one at a time.

We have to deal with the input state and the state on the job object (I think we call this globals), and the incoming configuration.

Start by locating the runtime code that assembles state objects and the unit tests covering strict mode. Trace the input state, job globals, and incoming configuration, then determine how unused data and configuration keys should be handled. Done means the unnecessary default keys and strict mode are removed consistently and the affected tests pass.