Standardize raster path pose direction

[marip8]

As of f250219254b99998aed179b3987bd413073fab07, the surface walk planner and plane slice planner generate the waypoint poses with different orientations for each segment. This becomes an issue in motion planning if you want to be able to switch from one tool path planner to the other because their outputs are not consistent.

Plane slice

Waypoint orientation changes by 180 degrees about the surface normal axis between adjacent raster segments

Surface walk

Waypoints are oriented in the same direction for all raster segments

These two planners should have the same behavior with respect to the way that waypoints are oriented in adjacent segments. I personally prefer the current plane-slice approach (180 rotation about surface normal between adjacent segments), but I'm not sure if there is a compelling reason to do otherwise. Maybe this should be handled by a parameter that indicates whether all segments should have the same orientation. Any thoughts?