Function execute_source 

fn execute_source<'a>(
    session: &'a mut CqlSession,
    config: &'a MergedConfig,
    shell: &'a mut ShellState,
    path: &'a str,
) -> Pin<Box<dyn Future<Output = ()> + 'a>>

Execute a SOURCE file: read CQL statements and execute them sequentially.

Shell commands in the file (SHOW, CONSISTENCY, etc.) are routed through dispatch_input just like interactive input — they are not sent to the DB.