VOL-2920 - Remove NBI passthrough functions.

Modified the NBIHandler to reference device, logical device, and adapter managers as embedded types, allowing the managers to directly implement API functions, without the need for individual passthrough functions.
Also created a new event.Manager type, which is embedded in device.LogicalManager.
Also renamed device.NewDeviceManagers() to device.NewManagers().

Change-Id: I8455da79b991ee67cc16cf898b00b0c98ea97bcd
diff --git a/rw_core/core/device/agent.go b/rw_core/core/device/agent.go
index 3857a6b..940bf1c 100755
--- a/rw_core/core/device/agent.go
+++ b/rw_core/core/device/agent.go
@@ -389,8 +389,8 @@
 	defer agent.requestQueue.RequestComplete()
 
 	device := agent.getDeviceWithoutLock()
-	dType := agent.adapterMgr.GetDeviceType(device.Type)
-	if dType == nil {
+	dType, err := agent.adapterMgr.GetDeviceType(ctx, &voltha.ID{Id: device.Type})
+	if err != nil {
 		return coreutils.DoneResponse(), status.Errorf(codes.FailedPrecondition, "non-existent-device-type-%s", device.Type)
 	}
 
@@ -479,8 +479,8 @@
 	defer agent.requestQueue.RequestComplete()
 
 	device := agent.getDeviceWithoutLock()
-	dType := agent.adapterMgr.GetDeviceType(device.Type)
-	if dType == nil {
+	dType, err := agent.adapterMgr.GetDeviceType(ctx, &voltha.ID{Id: device.Type})
+	if err != nil {
 		return coreutils.DoneResponse(), status.Errorf(codes.FailedPrecondition, "non-existent-device-type-%s", device.Type)
 	}
 
@@ -621,8 +621,8 @@
 	if device.OperStatus != voltha.OperStatus_ACTIVE || device.ConnectStatus != voltha.ConnectStatus_REACHABLE || device.AdminState != voltha.AdminState_ENABLED {
 		return coreutils.DoneResponse(), status.Errorf(codes.FailedPrecondition, "invalid device states")
 	}
-	dType := agent.adapterMgr.GetDeviceType(device.Type)
-	if dType == nil {
+	dType, err := agent.adapterMgr.GetDeviceType(ctx, &voltha.ID{Id: device.Type})
+	if err != nil {
 		return coreutils.DoneResponse(), status.Errorf(codes.FailedPrecondition, "non-existent-device-type-%s", device.Type)
 	}
 
@@ -1165,7 +1165,7 @@
 func (agent *Agent) getPorts(ctx context.Context, portType voltha.Port_PortType) *voltha.Ports {
 	logger.Debugw("getPorts", log.Fields{"device-id": agent.deviceID, "port-type": portType})
 	ports := &voltha.Ports{}
-	if device, _ := agent.deviceMgr.GetDevice(ctx, agent.deviceID); device != nil {
+	if device, _ := agent.deviceMgr.getDevice(ctx, agent.deviceID); device != nil {
 		for _, port := range device.Ports {
 			if port.Type == portType {
 				ports.Items = append(ports.Items, port)
@@ -1503,7 +1503,7 @@
 	}
 }
 
-func (agent *Agent) simulateAlarm(ctx context.Context, simulatereq *voltha.SimulateAlarmRequest) error {
+func (agent *Agent) simulateAlarm(ctx context.Context, simulateReq *voltha.SimulateAlarmRequest) error {
 	if err := agent.requestQueue.WaitForGreenLight(ctx); err != nil {
 		return err
 	}
@@ -1513,7 +1513,7 @@
 	cloned := agent.getDeviceWithoutLock()
 
 	subCtx, cancel := context.WithTimeout(context.Background(), agent.defaultTimeout)
-	ch, err := agent.adapterProxy.SimulateAlarm(subCtx, cloned, simulatereq)
+	ch, err := agent.adapterProxy.SimulateAlarm(subCtx, cloned, simulateReq)
 	if err != nil {
 		cancel()
 		return err