When launching an Investigation, Notify the Ccs

RT never shipped an On Create Notify Ccs Scrip, so you could add Ccs
to an Investigation but they would never see the initial mail.

In core, we're handling this by making new installs notify and
documenting for upgraders.  This avoids people who were relying on the
behavior from being surprised.  I've followed that lead here.
Merge branch '2.9/notify-ccs-on-investigation-launch' into 2.9-trunk