Use typeguard for runtime input validation.

[jaraco]

In #311 (comment)_, I explore the possibility of using typeguard (or pydantic but for the Rust build dependency) to perform parameter validation.

Although I'd love to have a built-in language feature to perform such validations (and other transforms), I haven't had the opportunity to drive this effort forward, so a third-party library is our only option.

[agriyakhetarpal]

Thanks for splitting it out here. Since this could be an incremental change over time, I can help out on this, and would like to, too.