Runtime: give the VM a name

[josephjclark]

When we get an error in the runtime, anything in the jobcode is said to belong to vm:module(0)

I'm sure that when we create the VM context, we can actually pass a name for the environment.

It would be ideal to use the step name (converted to a kebab-cased slug and maybe truncated to 10 or so characters) here.

This will also help the global functions