Move internal modules to “internal” folder.

.internal/stringToArray.js

@@ -0,0 +1,18 @@
+import asciiToArray from './.internal/asciiToArray.js';
+import hasUnicode from './.internal/hasUnicode.js';
+import unicodeToArray from './.internal/unicodeToArray.js';
+
+/**
+ * Converts `string` to an array.
+ *
+ * @private
+ * @param {string} string The string to convert.
+ * @returns {Array} Returns the converted array.
+ */
+function stringToArray(string) {
+  return hasUnicode(string)
+    ? unicodeToArray(string)
+    : asciiToArray(string);
+}
+
+export default stringToArray;