Feat

[spoj]

This pull request introduces a new example CLI application for extracting attachments from .msg files, along with some supporting changes to the library. The most important changes include adding a CLI example using clap, modifying the Attachment struct to make its fields public, and improving the filtering logic for attachment paths.

New CLI Example:

• Added an example CLI application in examples/extractor.rs that uses clap to parse arguments and demonstrates how to extract attachments and embedded messages from .msg files. This includes creating output directories, avoiding file overwrites, and recursively handling embedded messages.

Library Enhancements:

• Made the name and data fields of the Attachment struct public in src/lib.rs to allow external access, which is necessary for the CLI example to function.
• Improved the filtering logic for attachment paths in src/lib.rs by separating the map and filter operations, which simplifies the code and makes it more readable.

Dependency Updates:

• Added clap as a development dependency in Cargo.toml to support the new CLI example.