add pp_doclayout_v2 (#4863)

* add pp_doclayout_v2

* add safetensors loader

* update

Author: zhang-prog

paddlex/inference/models/object_detection/modeling/__init__.py

@@ -12,4 +12,5 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from .pp_doclayout_v2 import PPDocLayoutV2
 from .rt_detr import RTDETR