Fixed some CMake issues

[alireza-moayyedi]

Hi,

I wanted to use Cloudini in my project but not just the off the shelf topic converter node. I wanted to link directly against the libraries and use the available APIs in my source code. However, there were some issues that I had to fix:

• pcl_ros has more exported dependencies than the system library PCL. And annoyingly, find_package(pcl_ros) overwrites exported dependencies that come with find_package(PCL). So if a downstream project (as in my case) is using only find_package(PCL) in their cmake then there will be target was not found errors for targets such as usblib::usblib. Since in any case only COMMON and IO components of the PCL are being used in Cloudini, I removed pcl_ros references to keep it more lightweight and avoid unnecessary dependencies in downstream packages (although this is more of pcl_ros overwriting issue, but well, thought it would be better in any case to keep things efficient).
• Fixed cloudini_ros targets not being exported
  • ament_export_dependencies expects full package name so had to replace ${PLUGIN_DEPS} (as it includes targets) with the package names.

Some furthur improvements:

• PCL already exports its libraries as targets so things like ${PCL_INCLUDE_DIRS} are no more necessary
• Similarly, ament_export_include_directories or ament_export_libraries are also unnecessary as cloudini_ros now already exports targets.