Function run_generate_config 

fn run_generate_config<O: Output, C: ConfigManager>(
    output: &mut O,
    config_manager: &C,
    default_config_path: &str,
    hosts: Vec<String>,
    cluster: &str,
    program: Option<&str>,
    ssh_config_path: Option<&str>,
    arguments: Vec<String>,
    output_path: Option<&str>,
) -> Result<(), String>

Write the generated config to output_path (or default_config_path) and print its absolute path to output; error if hosts is empty or the write fails.