Kotlin: Add test for exposed internal representation

Author: tamasvajk

java/ql/test/kotlin/query-tests/ExposeRepresentation/ExposeRepresentation.expected

@@ -0,0 +1 @@
+| ExposesRep.kt:2:5:2:49 | getStrings | getStrings exposes the internal representation stored in field strings. The value may be modified $@. | User.kt:3:12:3:18 | User.kt:3:12:3:18 | after this call to getStrings |

java/ql/test/kotlin/query-tests/ExposeRepresentation/ExposeRepresentation.qlref

@@ -0,0 +1 @@
+Violations of Best Practice/Implementation Hiding/ExposeRepresentation.ql

java/ql/test/kotlin/query-tests/ExposeRepresentation/ExposesRep.kt

@@ -0,0 +1,3 @@
+class ExposesRep {
+    val strings: Array<String?> = arrayOfNulls(1)
+}

java/ql/test/kotlin/query-tests/ExposeRepresentation/User.kt

@@ -0,0 +1,5 @@
+class User {
+    fun test1(er: ExposesRep) {
+        er.strings[0] = "Hello world"
+    }
+}