Function get_simple_provider_boxed 

pub fn get_simple_provider_boxed(
    plaintext_prompt_func: Option<Box<dyn Fn(&str) -> Result<bool, Error<'static>> + Send>>,
) -> AuthProvider

Gets a simple authentication provider with a boxed callback.

This version accepts a boxed trait object, making it suitable for use with dynamic languages like Python. The callback is leaked to ensure it stays alive for the lifetime of the auth provider.

Safety

The boxed callback is intentionally leaked and will not be freed automatically. This is necessary because SVN holds onto the pointer for the lifetime of the auth system.