Kotlin: Add an extra test case for Kotlin array taint

Author: igfoo

java/ql/test-kotlin1/library-tests/dataflow/foreach/C2.kt

@@ -8,6 +8,7 @@ class C2 {
         val l = arrayOf(taint("a"), "")
         sink(l)
         sink(l[0])
+        sink(l.get(0))
         for (i in l.indices) {
             sink(l[i])
         }

java/ql/test-kotlin1/library-tests/dataflow/foreach/test.expected

@@ -4,5 +4,6 @@
 | C1.java:10:44:10:46 | "a" | C1.java:19:20:19:20 | s |
 | C2.kt:8:32:8:32 | "a" | C2.kt:9:14:9:14 | l |
 | C2.kt:8:32:8:32 | "a" | C2.kt:10:14:10:17 | ...[...] |
-| C2.kt:8:32:8:32 | "a" | C2.kt:12:18:12:21 | ...[...] |
-| C2.kt:8:32:8:32 | "a" | C2.kt:15:18:15:18 | s |
+| C2.kt:8:32:8:32 | "a" | C2.kt:11:14:11:21 | get(...) |
+| C2.kt:8:32:8:32 | "a" | C2.kt:13:18:13:21 | ...[...] |
+| C2.kt:8:32:8:32 | "a" | C2.kt:16:18:16:18 | s |