[fix][ROS2] Fix issues in keypoints extractors

Goal

Some issues merged with !324 (merged) for feat/ROS2, detected while cathing up master in !398 (merged).

Changes

• Add "pragma #once" in KeypointExtractor.h and DenseSpinningSensorKeypointExtractor.h
• Change degrees to radians in default values for AzimuthMin and AzimuthMax, change GetAzimuthMin() and GetAzimuthMax() (add conversion from radians to degrees)

What remains to solve

Issue for ParaView : Find out how to clear the Keypoints structure (which is a VoxelGrid) in SpinningSensorKeypointExtractor to keep the parameters set by the user instead of taking default parameters in the initialization.

• Note that the VoxelGrid is initialized by a Init() function taking this->VoxelResolution, instead of using a constructor.
• Note also that we changed the this->Keypoints[k].Clear() (using the Clear() method of VoxelGrid) to this->Keypoints.clear() (using the standard clear() method for a map) in !324 (merged)