error_handling/error_handler library

1. pubdev_test package
2. documentation
3. error_handling/error_handler.dart

pubdev_test package

1. Libraries
2. error_handling/error_handler
3. error_handling/error_response
4. helpers/date_helper
5. helpers/string_extensions
6. internet_checker/internet_checker
7. logging/logger
8. pubdev_test