The `CMAKE_LINK_LIBRARY_FILE_FLAG` variable is meant for linkers that
want library file paths to be preceded by a flag.  This is used only
for OpenWatcom to add the `library` argument before library file paths.
Refactor the approach to treat `CMAKE_LINK_LIBRARY_FILE_FLAG` as a
command-line string fragment to add just before the library file path.
This has two advantages:

* `CMAKE_LINK_LIBRARY_FILE_FLAG` now works like `CMAKE_LINK_LIBRARY_FLAG`.
* `CMAKE_LINK_LIBRARY_FILE_FLAG` can now be an attached flag whose value
  is the library file path.

Technically this is a change in behavior, but this setting was created
for internal use and should be rarely used outside of CMake itself.

Fixes: #19541