Install includes to include/${PROJECT_NAME}

[elfenpiff]

Brief feature description

Adds a CMake option APPEND_PROJECT_NAME_TO_INCLUDEDIR defaulting to ON
that appends ${PROJECT_NAME} to the directory headers are installed. This is to support ros2/ros2#1150.

Pretty similar to eclipse-cyclonedds/cyclonedds#1169

When using ROS 2 and Colcon it's possible to have two versions of a package installed: typically one from the debian packages (like ros-[rosdistro]-iceoryx-binding-c) and another in a from-source workspace. In Colcon terms this is called "overriding a package", and the /opt/ros/[rosdistro] folder would be called the underlay while the from-source workspace would be called the overlay. A user would do this when they want to try a newer version of a package without building everything from source.

When two or more packages install their headers to the same directory in an underlay, it becomes possible for packages in the overlay to accidentally find the headers of an overridden package in the underlay. This can cause build failures or undefined behavior at runtime depending on the differences between the headers in the overridden and overriding packages. The exact conditions this happens are a little complicated, so I'll skip writing it out here. In ROS 2 we're solving the issue by making every package install its headers to a unique folder using ${PROJECT_NAME}.

[elfenpiff]

FYI: @sloretz