Find LaserScan ray index in RViz for LaserScanMaskFilter

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I found two crappy workarounds that may work for some:

First method: Open a console big enough you can see the whole laserscan message when echoing the scan topic. Make sure there is enough space around your lidar and use an instance of LaserScanRangeFilter so all rays are NaN. Place an obstacle near the lidar. Use your eyes to visually scan the message dump until you spot which indexes affected rays have.

Second method: The lidar of my robot is smack in the middle, so i can just use the x/y coordinates of a single Point visible in the selection window of RViz to calculate the angle in rad and use LaserScanAngularBoundsFilter instead. Use enough numeric precision to statisfy the filter (remember that a single ray has 0.01744 rad).