reconsider complex env-var dict mechanism for associating autopara info with specific function calls

[bernstei]

The mechanism that's currently documented for passing remoteinfo to autopara ops in docs/source/overview.queued.md is quite complex (in its most general form). Even though I came up with it, I've mostly stopped using it.

Instead, I've switched to explicitly passing RemoteInfo objects (or dicts) in the actual function call, but obtaining those by importing from another file, to separate the task and the details for parallelizing on any given machine. E.g. I have a python file called remote_details.py, which contains

MD_operation = {"one_hpc_machine": { dict with remoteinfo stuff for that machine },
                "other_hpc_machine": {dict with remoteinfo stuff fot this other machine}
               }

which I then import, and when I call the autopara MD function I pass remoteinfo = remote_details.MD_operation["one_hpc_machine"].

I think this is versatile enough, and simpler from the view of the wfl implementation. We should consider removing the env-var based code, and revising the docs as needed.