Add CLI framework

[kaleidawave]

Want from a Rust CLI framework

• lightweight (no required dependencies)
• --help command for each endpoint
• For endpoints to be allowed a prefix for grouping
• Ability to use without macros
• Warn about additional arguments
• Provide an API that takes Vec<String> for testing

This is what this library provides

In the future it could

• Under cfg add completions for various shells
• Have a macro API for parsing into structures
• Have an identical API for JavaScript
• Have an exposed lint API so that during testing the structure could be checked