utils/barrels library

1. secugen_plugin package
2. documentation
3. utils/barrels.dart

secugen_plugin package

1. Libraries
2. models/image_capture_result
3. secugen_plugin
4. secugen_plugin_method_channel
5. secugen_plugin_platform_interface
6. utils/barrels
7. utils/constants
8. utils/sgfplib_exception