Kotlin: Add FP test case for mutual dependency query

Author: tamasvajk

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

@@ -0,0 +1 @@
+| Test.kt:5:9:5:41 |  | This type and type $@ are mutually dependent. | Test.kt:3:1:8:1 | Foo | Foo |

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

@@ -0,0 +1 @@
+Architecture/Dependencies/MutualDependency.ql

java/ql/test/kotlin/query-tests/MutualDependency/Test.kt

@@ -0,0 +1,8 @@
+package foo.bar
+
+class Foo {
+    private fun someFun() {
+        fun say(s: String) { println(s) }
+        say("Str")
+    }
+}