Created by: luotao1

fix #12198 (closed)

1. move contrib/inference to paddle/fluid/inference/api, and simplify the file name.

• The contrib directory only contains float16:

contrib/
└── float16
    ├── float16_benchmark.md
    ├── float16_inference_demo.py
    ├── float16_transpiler.py
    ├── README.md
    └── run_float16_demo.sh

• The fluid/inference/api directory likes:

fluid/inference/api/
├── api_anakin_engine.cc
├── api_anakin_engine.h
├── api_anakin_engine_tester.cc
├── api.cc
├── api.h
├── api_impl.cc
├── api_impl.h
├── api.map
├── api.sym
├── api_tensorrt_subgraph_engine.cc
├── check_symbol.sh
├── CMakeLists.txt
├── demo_ci
│   ├── CMakeLists.txt
│   ├── README.md
│   ├── run.sh
│   ├── simple_on_word2vec.cc
│   ├── utils.h
│   └── vis_demo.cc
├── high_level_api_cn.md
├── high_level_api.md
├── README.md
├── test_api.cc
├── test_api_impl.cc
└── test_api_tensorrt_subgraph_engine.cc

• after make inference_lib_dist, the fluid_install_dir/paddle/fluid/inference directory likes:

paddle/fluid/inference/
├── anakin
│   ├── anakin_release_simple.tar.gz
│   ├── libinference_anakin_api.a
│   └── libinference_anakin_api_shared.so
├── api.h
├── engine.h
├── io.h
├── libpaddle_fluid.a
├── libpaddle_fluid.so
├── libpaddle_inference_api.a
└── libpaddle_inference_api.so

NOTE: api.h is in the same level with io.h

2. after move, make demo_ci pass.

3. fix some format

paddle/fluid/inference/api/api_anakin_engine.cc:113:  You don't need a ; after a }  [readability/braces] [4]
paddle/fluid/inference/api/api_anakin_engine.cc:41:  Add #include <vector> for vector<>  [build/include_what_you_use] [4]
Done processing paddle/fluid/inference/api/api_anakin_engine.cc
Total errors found: 2
Done processing paddle/fluid/inference/api/api_anakin_engine_tester.cc
paddle/fluid/inference/api/api_impl.cc:108:  You don't need a ; after a }  [readability/braces] [4]
Done processing paddle/fluid/inference/api/api_impl.cc
Total errors found: 1
Done processing paddle/fluid/inference/api/api_impl.h
Done processing paddle/fluid/inference/api/api_tensorrt_subgraph_engine.cc
paddle/fluid/inference/api/test_api.cc:17:  Found C system header after other header. Should be: test_api.h, c system, c++ system, other.  [build/include_order] [4]
paddle/fluid/inference/api/test_api.cc:18:  Found C system header after other header. Should be: test_api.h, c system, c++ system, other.  [build/include_order] [4]
Done processing paddle/fluid/inference/api/test_api.cc
Total errors found: 2
paddle/fluid/inference/api/test_api_impl.cc:18:  <thread> is an unapproved C++11 header.  [build/c++11] [5]
Done processing paddle/fluid/inference/api/test_api_impl.cc
Total errors found: 1
Done processing paddle/fluid/inference/api/test_api_tensorrt_subgraph_engine.cc

fixes: #12185