ServiceManager signals init to start lazy services

This allows services to be disabled at boot and dynamically enabled as
they are needed. When servicemanager receives a getService request,
it will check whether the service is running. If it is not,
servicemanager will attempt to start the service by signaling init with
the ctl.interface_start control message.

Bug: 138756857
Test: Manual (using mediaextractor as a test service), test_sm
Change-Id: Ic2d47d21769b936381e3fae2f2cf739d3b7501a4