Add tests to #638 array parsing issue

cases array length is 0 or 1.

examples/arrays.ion

 # Standard Arrays
 
+let array = []
+echo @array
+
+let array = [1]
+for i in @array
+    echo $i
+end
+
 let array = [1  [2 3]  4 [5 6]]
 for i in @array
     echo $i

examples/arrays.out

+
+1
 1
 2
 3