DevMgr: attachAllUnattachedDevsFrom: now takes sh_ptr<vector<Spec>>

This method now accepts a sh_ptr<vector<DeviceAttachmentSpec>> to
tell it specifically which specs to attempt to attach.

This enables us to implement different frontends that supply it
with collections of devices from different sources (GUI, cmdline,
previously failed-to-attach/hot-removed devices, etc).

SMO temporarily initializes none of the devices from the cmdline
during this commit as we transition to implementing the cmdline
collection frontend.

smocore/body/body.cpp

@@ -79,6 +79,7 @@ public:
 				<< '\n';
 		}
 		device::DeviceManager::getInstance().attachAllUnattachedDevicesFromReq(
+				std::make_shared<std::vector<device::DeviceAttachmentSpec>>(),
 				{context, std::bind(
 					&InitializeReq::initializeReq2,
 					context.get(), context,