Function write_binary_ppm 

pub fn write_binary_ppm(
    canvas: &Canvas<Vector3<u8>>,
    directory: &Path,
    file_name: &str,
) -> Result<(), Box<dyn Error>>

Writes the image data to the specified path

Takes a directory and file name and writes the image to that directory.

If an image already exist with the specified name, it will be overwritten.

The file path and file name are separate to allow for easier file management.

Example usage:

let my_path = Path::new("./");
let my_canvas = Canvas<Vector3<u8>>::new(500, 500);
write_to_file(&my_canvas, &my_path, "my_image_name");