FIx missing dependency to build on ROS 2 Jazzy

[lreiher]

Building on ROS 2 Jazzy ...

docker run --rm -it -v $(pwd):/ws/src/ros-sharp ros:jazzy
# ---
cd /ws
colcon build --packages-up-to file_server2 unity_simulation_scene2 gazebo_simulation_scene2

... currently results in the error below, which is fixed with this PR.

root@5a79217e987e:/ws# colcon build --packages-up-to file_server2
Starting >>> file_server2
--- stderr: file_server2                               
/ws/src/ros-sharp/ROS Packages/ROS2/file_server2/src/file_server.cpp:21:10: fatal error: ament_index_cpp/get_package_share_directory.hpp: No such file or directory
   21 | #include <ament_index_cpp/get_package_share_directory.hpp>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
gmake[2]: *** [CMakeFiles/file_server2_node.dir/build.make:76: CMakeFiles/file_server2_node.dir/src/file_server.cpp.o] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:625: CMakeFiles/file_server2_node.dir/all] Error 2
gmake: *** [Makefile:146: all] Error 2
---
Failed   <<< file_server2 [13.3s, exited with code 2]

Summary: 0 packages finished [13.7s]
  1 package failed: file_server2
  1 package had stderr output: file_server2