We can't tag on instance creation when we're in "restricted" regions,
so let's add the tags after the resources have been created.
Adds methods to AccessConfig to detect if we're in China or US Gov
regions (i.e. "restricted").
Also turns tag:tag maps into a type, and moves methods around validating
and converting them to ec2Tags to methods of the type.
Run now takes a context as well as a statebag. We'll assign the context
to the blank identifier to prevent namespace collisions. We'll let the
step authors opt-in to using the context.
`find . -iname "step_*.go" -exec gsed -i'' 's/func \(.*\)Run(/func \1Run(_ context.Context, /' {} \;`
StepTagEBSVolumes is no longer needed, since this functionality is now
taken over by StepRunSourceInstance and StepRunSpotInstance. So remove
this functionality from the codebase.
