Function validate_password 

pub fn validate_password(
    tool: PrivilegeTool,
    password: &str,
) -> Result<bool, String>

What: Validate a password against the privilege tool.

Inputs:

• tool: Resolved privilege tool.
• password: Password to validate.

Output:

• Ok(true) if valid, Ok(false) if invalid.
• Err if the tool doesn’t support stdin password or the check fails.

Errors

• Returns Err if the tool does not support stdin password validation.
• Returns Err if the validation command cannot be executed.

Details:

• Only works for tools with supports_stdin_password (currently sudo only).
• First invalidates cached credentials, then tests the password.