Do any propellers/propfans use stator vanes? Why is this not a commonplace feature?
When a compressor rotor stage speeds up the flow, the stator:


Slows it back down, turning kinetic energy into pressure (see image here from the book The Jet Engine)
Presents the flow at the correct angle for the next rotor stage.


A nozzle guide vanes stage (what a turbine stator stage likes to be called) comes before the turbine stage, and it does the same but in reverse (turns pressure into velocity) and adjusts the flow direction for the upcoming turbine stage.

The de-swirl function of the stator stage behind a fan in a turbofan (the outlet guide vanes – OGVs) is beneficial because of how much air the fan has acted on.

The number (and size) of blades tell the whole story. It's often said that propellers move air by a little, and jet engines by a lot. To put that into perspective, the typical pressure ratio rise behind a fan is 1.4–1.6, whereas behind a propeller it's less than 1.02.$^1$

This is where a turbofan's OGVs become beneficial. Adding a static stage of blades behind a propeller (with or without a case) that doesn't accelerate the air by that much to recover meaningful pressure (compared to a turbofan's fan, not much kinetic energy to begin with) in the axial direction won't help. On the contrary it will add drag (air hitting a static object), and weight.


  
    Actively contra-rotating both props adds a lot of complexity, and seems somewhat unnecessary if the goal is mostly to remove large part of the swirling motion. Cancelling all torque is not necessary for a plane.
  


A propeller is like a wing, it needs to act on (hit) air to create a normal force. If we substitute the second set of moving prop blades with static ones, we've just lost a lot of thrust.



$^1$: https://history.nasa.gov/SP-468/ch10-3.htm