Revert some of Elena's changes as they broke the ess/pmi component by making it too slurm-specific. Update the pmix/s1 component to get it properly integrated with the ess/pmi operation.

There is still something wrong in the slurm support, however. When we "fetch all keys" for a proc, I'm not seeing anything getting stored to dstore - I see the get_packed function retrieve something, but it appears to be failing to decode it properly