Bug 7469: Advertise CDS DOMDataTreeCommitCohortRegistry

Advertised the CDS DOMDataTreeCommitCohortRegistry implementation
via the DOMDataBrokerExtension mechanism.

I needed to add a DOMDataTreeCommitCohortRegistry interface version
in the controller DOM API package that extends the controller
DOMDataBrokerExtension since the mdsal DOMDataTreeCommitCohortRegistry
version extends the mdsal DOMDataBrokerExtension.

Change-Id: I71daac1cd7c231d071c376206d85786c333bac68
Signed-off-by: Tom Pantelis <tpanteli@brocade.com>