Maestro/flux synchronization of `exclusive` at the command line when running flux

[murray55]

Currently, when exclusive: True is specified in a study step, it places a --exclusive flux directive in the header of the batch scripts. There is a need to add --exclusive to the command line that is generated via the $(LAUNCHER) keyword as well.

[doutriaux1]

@jwhite242 can you please take a look at this? Thanks.

[jwhite242]

@murray55 Check out the 1.2.0 syntax to control this and let us know if there's anything still missing with the $(LAUNCHER) tokens (or the docs). Here's a few examples to show how it works: https://maestrowf.readthedocs.io/en/latest/Maestro/specification.html#exclusive-examples