Move internal modules to “internal” folder.

.internal/arraySampleSize.js

@@ -0,0 +1,17 @@
+import baseClamp from './.internal/baseClamp.js';
+import copyArray from './.internal/copyArray.js';
+import shuffleSelf from './.internal/shuffleSelf.js';
+
+/**
+ * A specialized version of `sampleSize` for arrays.
+ *
+ * @private
+ * @param {Array} array The array to sample.
+ * @param {number} n The number of elements to sample.
+ * @returns {Array} Returns the random elements.
+ */
+function arraySampleSize(array, n) {
+  return shuffleSelf(copyArray(array), baseClamp(n, 0, array.length));
+}
+
+export default arraySampleSize;