Iterate through all categories and break them into two columns

foreach( $categories as $category).php

<?php 
foreach( $categories as $category ) {
  $cat_count ++;
  $category_link = sprintf( 
      '<li class="list-unstyled"><a href="%1$s" alt="%2$s">%3$s</a></li>',
      esc_url( get_category_link( $category->term_id ) ),
      esc_attr( sprintf( __( 'View all posts in %s', 'textdomain' ), $category->name ) ),
      esc_html( $category->name )
  );
  if ($cat_count % 2 != 0 ) {
    $cat_col_one[] = $category_link;
  } else {
    $cat_col_two[] = $category_link;
  }
}
?>