R Version 2: Differentiate globally versus locally valid data

[SteVwonder]

There a few pieces of information that are useful/necessary to include in R but that should not be ingested by sub-instances because it is only valid in the current instance. Two examples include:

1. Rank information
2. The label passed through from jobspec onto matched resources

It would be nice if we had a space in R dedicated to this, that sub-instances can (and should) ignore. In the strawman in flux-framework/flux-sched#743, we added an "ephemeral" key containing a dict to each resources within JGF. This stores the locally valid jobspec label information.