Add Variable for List of Dependency Link Targets

[kilo52]

In the dependency() function provided by C and C++ project source templates of project-init, add a function parameter to allow a dependency declaration to specify a list of targets that should be appended to a list in the CMake cache. This can then be used by projects in calls to the CMake target_link_libraries() function to automatically link all targets that are declared dependencies of the underlying project. The benefit is that simply adding a new dependency automatically sets up the linking to the dependency targets in a basic setting. This is less error prone than having to remember to add those targets to the call to the target_link_libraries() function.