Global assistant: Receive several job code step changes

[hanna-paasivirta]

Is your feature request related to a problem? Please describe.
Lightning should only receive full YAMLs with job code embedded from the Global Assistant on Apollo. This will enable viewing and applying several job code step changes. More details here OpenFn/apollo#507

[josephjclark]

@hanna-paasivirta this feels like a twin / duplicate of OpenFn/apollo#456 right?

[hanna-paasivirta]

@josephjclark This one is focused on basic functionality, with no visualisation improvements.