ENH: Disallow link-type keywords in link interface

The LINK_INTERFACE_LIBRARIES target property may not contain the
"debug", "optimized", or "general" keywords.  These keywords are
supported only by the target_link_libraries (and link_libraries) command
and are not a generic library list feature in CMake.  When a user
attempts to add one of these keywords to the property value, we now
produce an error message that refers users to alternative means.