[FEA]: Add python bindings for construction of a RouterStage<ControlMessage>

[drobison00]

Is this a new feature, an improvement, or a change to existing functionality?

New Feature

How would you describe the priority of this feature request

High

Please provide a clear description of problem this feature solves

Building multi-function pipelines will benefit tremendously from having these primitives.

Currently Morpheus emulates routing behavior using a broadcast-and-filter pattern, which works, but its clunky and non-intuitive as we expand the number of people who will be building out application pipelines.

We currently have a Router operator defined in (cpp/mrc/include/mrc/node/operators/router.hpp) : this needs to have python bindings written for a single specialization ControlMessage -> ControlMessage.

Describe your ideal solution

We would like to support something like the following:

def routing_criteria(msg: ControlMessage):
  if (criteria_0(msg)):
      # route to output 0
      
  if (criteria_1(msg)):
      # route to output 1
      
  ... snip ...  
pipe = Pipeline(...)

stage_a = pipe.add_node(...)
stage_b = pipe.add_node(...)
stage_c = pipe.add_node(...)
router = pipe.add_node(RouterStage(route_fn = routing_criteria))

pipe.add_edge(stage_a, router)
pipe.add_edge(router, stage_b)  # Route here for criteria 0
pipe.add_edge(router, stage_c)  # Route here for criteria 1

Additional context

No response

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