Helpers: Handled edge case.
When target file is outside project directory,
ProjectItems.AddFromFile( .. ) throws
COMException: "Webs do not support linked files."

For instance, it will throw exception if custom
folder in compiler is set to absolute or relative
path, which yields a location outside
the project scope.

For instance, if custom folder in compiler is
set with absolute or relative path, which yeilds
a location outside the project scope.