title: Split string every n characters
body: <p>What would be an idiomatic way to split a string into strings of 2 characters each?</p>
  
  <p>Examples:</p>
  
  <pre><code>"" -&gt; [""]
  "ab" -&gt; ["ab"]
  "abcd" -&gt; ["ab", "cd"]
  </code></pre>
  
  <p>We can assume that the string has a length which is a multiple of 2.</p>
  
  <p>I could use a regex like in <a href="https://stackoverflow.com/a/4788718/829571">this Java answer</a> but I was hoping to find a better way (i.e. using one of kotlin's additional methods).</p>