Modify file structure to separate python and cpp code (#223)

Modify code structure

python/fastdeploy/__init__.py

@@ -0,0 +1,28 @@
+# Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from __future__ import absolute_import
+import logging
+import os
+import sys
+
+from .c_lib_wrap import (Frontend, Backend, FDDataType, TensorInfo, Device,
+                         is_built_with_gpu, is_built_with_ort,
+                         is_built_with_paddle, is_built_with_trt,
+                         get_default_cuda_directory)
+from .runtime import Runtime, RuntimeOption
+from .model import FastDeployModel
+from . import c_lib_wrap as C
+from . import vision
+from . import text
+from .download import download, download_and_decompress