Dynamically manage libraries in external build files

The VTK-m build creates a makefile and a package file that allows external projects that do not use VTK-m to easily import the compile flags needed to use VTK-m. However, the list of libraries to link is a static list. This is problematic, particularly with the new filter organization that splits to filters into an ever-growing list of libraries.

The CMake configuration should be changed to automatically update this list of libraries based on what is available in the source and what is actually compiled.