Add AbstractFactoryRegistry class, and tests.

This class will be used to create registries of key and operation
factories, to decouple the GoogleKeymaster implementation from the set
of supported algorithms and operations.  In particular, this will allow
the GetSupported*() methods to query the factories, rather than
duplicating the supported lists.

Change-Id: I7899ed579414bffa2056b61ba51faeba26fd2134
5 files changed