Draft: Conan2 implementation

This is a test, trying to implement conan2 for CORSIKA8. I believe that all packages that we need for CORSIKA8 are now available (and working). This is based on the PR !552 (closed).

Instead of executing 'conan_install.sh', the commands that are currently used are:

conan install ../corsika --output-folder=.
cmake ../corsika -DCMAKE_BUILD_TYPE="RelWithDebInfo" -DCMAKE_INSTALL_PREFIX=../corsika-install -DCMAKE_TOOLCHAIN_FILE=conan/conan_toolchain.cmake

However, I failed to properly combine this with the CMake structure of CORSIKA8, especially regarging the test and corsika-data environment. Maybe someone who understands this system (or CMake in general) better might have a look at this 😅 Anyways, this PR is rather intended to be a starting point for the implementation of conan2. Because if we decide to stay with conan (or at least support it in the future), we should mitigate to conan2 before conan1 becomes deprecated.