add proper GaussianSplattingViewer argument parsing

[github-actions]

bevy_gaussian_splatting/viewer/viewer.rs

Line 61 in cd9fd07

// TODO: add proper GaussianSplattingViewer argument parsing

        ..default()
    };

    // TODO: add proper GaussianSplattingViewer argument parsing
    let file_arg = std::env::args().nth(1);
    if let Some(n) = file_arg.clone().and_then(|s| s.parse::<usize>().ok()) {
        println!("generating {} gaussians", n);
        cloud = gaussian_assets.add(random_gaussians(n));