Pointcloud reflectivity filtering & lidar blockage detection

[KStew8111]

Is your feature request related to a problem? Please describe.
In the ROS1 version of the driver we had added the ability to filter out points based on its reflectivity value inside a certain range from the sensor, as well as determining if the sensor was blocked by looking at the amount of points inside of the minimum range of the sensor.

Describe the solution you'd like
We would like to be able to filter the pointcloud by eliminating points that are below a reflectivity threshold and within a certain range of the sensor. This would allow us to prevent things like dust clouds from appearing in the point cloud. We would also like to be able to sense if there is something inside of the sensor's minimum recommended range that could be blocking the lidar.

Describe alternatives you've considered
Filter nodes external to the driver that would come before the rest of the processing pipeline. Unsure of how additional nodes would affect overall performance.

Targeted Platform (please complete the following information only if applicable, otherwise dot N/A):

• Ouster Sensor? OS0
• Ouster Firmware Version? N/A
• ROS version/distro? ROS2 Humble
• Operating System? Ubuntu 20.04/22.04
• Machine Architecture? N/A