Kotlin: Add FP test case for one stmt in line query

Author: tamasvajk

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

@@ -0,0 +1 @@
+| Test.kt:5:9:5:23 | return ... | This statement is followed by another on the same line. |

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

@@ -0,0 +1 @@
+Advisory/Statements/OneStatementPerLine.ql

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

@@ -0,0 +1,7 @@
+class Foo {
+    fun foo(): Foo { return this }
+
+    fun bar(x: Foo?): Foo? {
+        return x?.foo()
+    }
+}