Hide CarrierMessagingServiceWrapper for now.

Based on api-council feedback there are some changes required.
Will incorporate the changes and expose this class in a later
release.

Test: basic sanity
Bug: 144346062
Merged-in: Icb65f90261ea6000aecd72a1888d5ee23eed6527
Change-Id: Icb65f90261ea6000aecd72a1888d5ee23eed6527
(cherry picked from commit e75a35d3)