We have to introduce the kinda hacky concept of a 'No Stack' stack
to reconcile it with the idea of a 'default' k8s namespace. This is important
because swarm services without a stack don't have the same docker labels as ones that do.
Curiously, they still have what appears to be a stack name 'prefix' on their names,
but I can't isolate that name anywhere easily so they'll just have to make do.
I basically copy-pasted updateFilters to make this work, todo go back and refactor
to not duplicate 90% of the code.
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