Add ability to set dual return type

[mitch-galea]

It would be great to be able to configure the dual return type (ie strongest return vs furthest return vs nearest return) in the launch file. We currently run a fleet with ousters and being able to dynamically change this setting will be really useful and save us having to manually modify the setting for each Ouster

It is currently possible to enable dual returns but not configure the type

[Samahu]

Which ROS are you targeting currently?

[mitch-galea]

Thanks for the fast response, currently targeting noetic.