Function run_bet_with_progress 

pub fn run_bet_with_progress<F>(
    data: &[f64],
    nx: usize,
    ny: usize,
    nz: usize,
    vsx: f64,
    vsy: f64,
    vsz: f64,
    fractional_intensity: f64,
    smoothness_factor: f64,
    gradient_threshold: f64,
    iterations: usize,
    subdivisions: usize,
    progress_callback: F,
) -> Vec<u8> 
where
    F: FnMut(usize, usize),

Run BET brain extraction with progress callback

Same as run_bet but calls progress_callback(iteration, total_iterations) periodically