Add backend implementation to get devices not in a group.

# Conflicts:
#	components/device-mgt/io.entgra.device.mgt.core.device.mgt.core/src/main/java/io/entgra/device/mgt/core/device/mgt/core/service/DeviceManagementProviderService.java
#	components/device-mgt/io.entgra.device.mgt.core.device.mgt.core/src/main/java/io/entgra/device/mgt/core/device/mgt/core/service/DeviceManagementProviderServiceImpl.java

             persistedDevice.setName(device.getName());
             System.out.println("This is rename device");
-            boolean responseOfmodifyEnrollment = deviceManagementProviderService.modifyEnrollment(persistedDevice);
+            boolean responseOfRenameDevice = deviceManagementProviderService.updateDeviceName(persistedDevice);

+            boolean response = responseOfRenameDevice && responseOfDeviceNameChanged;
 
             return Response.status(Response.Status.CREATED).entity(response).build();
         } catch (DeviceManagementException e) {

+                log.debug("Device Manager associated with the device type '" + device.getType() + "' is null. " +
+                        "Therefore, not attempting method 'modifyEnrolment'");
+            }
+            return false;

+            int tenantId = this.getTenantId();
+            Device currentDevice = this.getDevice(deviceIdentifier, false);
+            device.setId(currentDevice.getId());
+            if (device.getName() == null) {

+
+            deviceDAO.updateDevice(device, tenantId);
+            DeviceManagementDAOFactory.commitTransaction();
+

                     (deviceId, deviceType), true);
             persistedDevice.setName(device.getName());
             System.out.println("This is rename device");

+
+    @Override
+    public Device updateDeviceName(Device device) throws DeviceManagementException {
+        int tenantId = this.getTenantId();

+        if (device == null) {
+            String msg = "Required values are not set to rename device";
+            log.error(msg);
+            throw new DeviceManagementException(msg);

+            DeviceManagementDAOFactory.commitTransaction();
+            this.removeDeviceFromCache(deviceIdentifier);
+            return device;
+

+            return device;
+
+        } catch (DeviceManagementDAOException e) {
+            String msg = "Error occurred while renaming the device '" + device.getId() + "'";

+            String msg = "Error occurred while initiating transaction to rename device: " + device.getId();
+            log.error(msg, e);
+            throw new DeviceManagementException(msg, e);
+        } catch (Exception e) {

             Device persistedDevice = deviceManagementProviderService.getDevice(new DeviceIdentifier

             Device persistedDevice = deviceManagementProviderService.getDevice(new DeviceIdentifier
                     (deviceId, deviceType), true);
             persistedDevice.setName(device.getName());