adjust infrastructure for example building

[derived-coder]

I cannot build the examples out of the box. Several reason:

1. I use a docker image where I have setup clang-uml, so it is in the path
   would be nice if you can adjust the makefiles so that it takes by default clang-uml from the current path and not from some relative path
2. several examples need dependencies, which I do not have so I cannot setup the build commands.
   e.g.:curl

CMake Error at /usr/local/share/cmake-3.29/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
  Could NOT find Libpsl (missing: LIBPSL_INCLUDE_DIR LIBPSL_LIBRARY)
Call Stack (most recent call first):
  /usr/local/share/cmake-3.29/Modules/FindPackageHandleStandardArgs.cmake:600 (_FPHSA_FAILURE_MESSAGE)
  CMake/FindLibpsl.cmake:68 (find_package_handle_standard_args)
  CMakeLists.txt:1291 (find_package)

I recommend that you setup a docker image for development, so it would be easy to rebuild the examples.

[bkryza]

@derived-coder Hi, I've actually attempted that a few times but always gave for some reason, usually it was related to issues with dependencies for different example projects needing different versions. Now that I think of it, I think I will try to do another approach.

1. Create a base docker common for all dependencies: clang-uml-examples-base
2. For each of the projects, I will create a separate docker image inheriting from base clang-uml-examples-base, e.g. clang-uml-examples-curl.
3. Then on top of these dockers I will create dockers for new version of clang-uml, e.g. clang-uml-examples-curl:0.6.0
4. Add the dockers to the Makefile so that the examples are always reproducible...

[derived-coder]

Why not make one docker image for all examples, which contain all dependencies?

[bkryza]

@derived-coder Like mentioned above I've tried that but I was hitting issues with conflicting dependencies needed by different examples. Also separate Docker images will be much easier to maintain and smaller if you're just interested in a specific example. With 1 Docker image I would have to rebuild the image every time I'd add a new example or when I would need to update it's dependencies...