feat: 切换后端至PaddleOCR-NCNN，切换工程为CMake

1.项目后端整体迁移至PaddleOCR-NCNN算法，已通过基本的兼容性测试
2.工程改为使用CMake组织，后续为了更好地兼容第三方库，不再提供QMake工程
3.重整权利声明文件，重整代码工程，确保最小化侵权风险

Log: 切换后端至PaddleOCR-NCNN，切换工程为CMake
Change-Id: I4d5d2c5d37505a4a24b389b1a4c5d12f17bfa38c

3rdparty/opencv-4.5.4/modules/videoio/cmake/plugin.cmake

@@ -0,0 +1,56 @@
+function(ocv_create_builtin_videoio_plugin name target)
+
+  ocv_debug_message("ocv_create_builtin_videoio_plugin(${ARGV})")
+
+  if(NOT TARGET ${target})
+    message(FATAL_ERROR "${target} does not exist!")
+  endif()
+  if(NOT OpenCV_SOURCE_DIR)
+    message(FATAL_ERROR "OpenCV_SOURCE_DIR must be set to build the plugin!")
+  endif()
+
+  message(STATUS "Video I/O: add builtin plugin '${name}'")
+
+  foreach(src ${ARGN})
+    list(APPEND sources "${CMAKE_CURRENT_LIST_DIR}/src/${src}")
+  endforeach()
+
+  add_library(${name} MODULE ${sources})
+  target_include_directories(${name} PRIVATE "${CMAKE_CURRENT_BINARY_DIR}")
+  target_compile_definitions(${name} PRIVATE BUILD_PLUGIN)
+  target_link_libraries(${name} PRIVATE ${target})
+
+  foreach(mod opencv_videoio opencv_core opencv_imgproc opencv_imgcodecs)
+    ocv_target_link_libraries(${name} LINK_PRIVATE ${mod})
+    ocv_target_include_directories(${name} "${OPENCV_MODULE_${mod}_LOCATION}/include")
+  endforeach()
+
+  if(WIN32)
+    set(OPENCV_PLUGIN_VERSION "${OPENCV_DLLVERSION}" CACHE STRING "")
+    if(CMAKE_CXX_SIZEOF_DATA_PTR EQUAL 8)
+      set(OPENCV_PLUGIN_ARCH "_64" CACHE STRING "")
+    else()
+      set(OPENCV_PLUGIN_ARCH "" CACHE STRING "")
+    endif()
+  else()
+    set(OPENCV_PLUGIN_VERSION "" CACHE STRING "")
+    set(OPENCV_PLUGIN_ARCH "" CACHE STRING "")
+  endif()
+
+  set_target_properties(${name} PROPERTIES
+    CXX_STANDARD 11
+    CXX_VISIBILITY_PRESET hidden
+    DEBUG_POSTFIX "${OPENCV_DEBUG_POSTFIX}"
+    OUTPUT_NAME "${name}${OPENCV_PLUGIN_VERSION}${OPENCV_PLUGIN_ARCH}"
+  )
+
+  if(WIN32)
+    set_target_properties(${name} PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${EXECUTABLE_OUTPUT_PATH})
+    install(TARGETS ${name} OPTIONAL LIBRARY DESTINATION ${OPENCV_BIN_INSTALL_PATH} COMPONENT plugins)
+  else()
+    install(TARGETS ${name} OPTIONAL LIBRARY DESTINATION ${OPENCV_LIB_INSTALL_PATH} COMPONENT plugins)
+  endif()
+
+  add_dependencies(opencv_videoio_plugins ${name})
+
+endfunction()