Proper supplementary service notification handling (1/5).

Remove CAF's passing of implementation details from the base classes,
and replace it by well-defined call properties.

Change-Id: I4fa94d4ba68a1570d3f822be569ae124882c0e66
(cherry picked from commit 2c7fc938d49e8b55f9105f5945f5d18e177a8a5c)