nav2_waypoint_follower: Fix opencv includes

[traversaro]

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Basic Info

Info	Please fill out this column
Ticket(s) this addresses	No tickets.
Primary OS tested on	Windows
Robotic platform tested on	Not tested in any robot, it is a compilation-related change.
Does this PR contain AI generated software?	No

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Description of contribution in a few bullet points

The path used for opencv includes in nav2_waypoint_follower was different from the one documented by opencv itself for its header, see for example:

• https://github.com/opencv/opencv/blob/4.9.0/samples/gpu/video_reader.cpp#L12
• https://github.com/opencv/opencv/blob/4.9.0/doc/tutorials/introduction/linux_gcc_cmake/linux_gcc_cmake.markdown?plain=1#L32

and from how other ROS 2 packages include opencv headers, see:

• https://github.com/ros-perception/vision_opencv/blob/4.1.0/cv_bridge/include/cv_bridge/rgb_colors.hpp#L39

In all cases the opencv4 part of the include path is not included, and on some platforms (in my case, Windows with libopencv installed via conda-forge) including it results in compilation errors such as:

2024-04-30T19:39:27.9695139Z %SRC_DIR%\ros-humble-nav2-waypoint-follower\src\work\include\nav2_waypoint_follower/plugins/photo_at_waypoint.hpp(35,10): fatal error C1083: Cannot open include file: 'opencv4/opencv2/core.hpp': No such file or directory [%SRC_DIR%\build\photo_at_waypoint.vcxproj]

As removing the opencv4 the compilation should work fine on all supported nav2 platforms, I guess it should be ok to uniform the opencv inclusion style with official OpenCV documentation and the rest of ROS 2.

Description of documentation updates required from your changes

No documentation changes should be required.

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Future work that may be required in bullet points

For Maintainers:

• Check that any new parameters added are updated in navigation.ros.org
• Check that any significant change is added to the migration guide
• Check that any new features OR changes to existing behaviors are reflected in the tuning guide
• Check that any new functions have Doxygen added
• Check that any new features have test coverage
• Check that any new plugins is added to the plugins page
• If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists

[SteveMacenski]

Admittedly we don't have many windows users, so I'm not surprised :-) Let CI turn over but LGTM

[traversaro]

Admittedly we don't have many windows users, so I'm not surprised :-) Let CI turn over but LGTM

To be honest, I was even surprised of finding it as an option in the PR template table. :D

[SteveMacenski]

There are Nav2 Windows users/tickets, but not many

Thanks! Looks like this builds fine on Linux as well!

[traversaro]

Thanks for the fast feedback!