Kotlin: Add FP test case for ignored return value query

Author: tamasvajk

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

@@ -0,0 +1 @@
+| Test.kt:14:29:14:33 | foo(...) | The result of the call is ignored, but 90% of calls to foo use the return value. |

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

@@ -0,0 +1 @@
+Likely Bugs/Statements/ReturnValueIgnored.ql

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

@@ -0,0 +1,16 @@
+class Foo {
+    fun foo(): Int { return 5 }
+    fun bar() {
+        val x0 = foo()
+        val x1 = foo()
+        val x2 = foo()
+        val x3 = foo()
+        val x4 = foo()
+        val x5 = foo()
+        val x6 = foo()
+        val x7 = foo()
+        val x8 = foo()
+        val x9 = foo()
+        val x = if (true) { foo() } else 6
+    }
+}