export dependency libraries automatically

[ClausKlein]

I had to add the known dependency for a library manually to cmake/install-config.cmake

But it should and may be generated.

# ---- add dependenc libraries ----

 find_package(Threads REQUIRED)
 target_link_libraries(asio_asio INTERFACE Threads::Threads)

see https://discourse.cmake.org/t/featuresummary-module-how-to-get-all-dependency-libraries-of-a-target-and-their-versions/5308

[friendlyanon]

That gets generated when a package manager is used for the project types where it's appropriate: https://github.com/friendlyanon/cmake-init/blob/develop/cmake-init/templates/common/cmake/install-config.cmake

There is also the transitive dependency example from before package manager support was added: https://github.com/friendlyanon/cmake-init-transitive