How to create a package that only contains launch files

edit

I want to create a package that only holds launch files for packages that I installed using apt-get. Let's say my package, called ros-package has the following folder structure:

.
├── CMakeLists.txt
├── launch
│   ├── a.launch
│   ├── all.launch
│   ├── b.launch
│   └── c.launch
└── package.xml

I want a.launch, b.launch, and c.launch each look something like this:

<launch>
    <node name="listener_node" pkg="hello_world" type="listener" output="screen"/>
</launch>

and all.launch just includes the other three and launches all of them. So I want to be able to "build" this package with catkin or colcon, source install/setup.bash, and run all with the following command:

roslaunch ros-package all.launch

Now I'm not sure how to setup the CMakeLists.txt and package.xml files to achieve this. Any help would be much appreciated.

With anything I've attempted the launch files don't get included in the install directory and are not found as a result.

Bonus question: I also have a config.yml file that I want to be copied into the install directory as well as it is passed on as an argument to one of the launch files.