custom_lint/unnecessary_container library

1. rexios_lints package
2. documentation
3. custom_lint/unnecessary_container.dart

rexios_lints package

1. Libraries
2. custom_lint/do_not_use_raw_paths
3. custom_lint/do_not_use_stateful_builder
4. custom_lint/double_leading_zero
5. custom_lint/inline_context_lookups
6. custom_lint/prefer_async_await
7. custom_lint/prefer_immutable_classes
8. custom_lint/prefer_timestamps
9. custom_lint/unnecessary_container
10. custom_lint/utils
11. rexios_lints