Kotlin: add test for not found equivalent of MutableList.remove

java/ql/test/kotlin/library-tests/java-map-methods/test.expected

@@ -1,4 +1,5 @@
 diagnostics
+| file://:0:0:0:0 | Couldn't find a Java equivalent function to kotlin.collections.MutableList.remove in java.util.List |
 #select
 | Integer |
 | Object |

java/ql/test/kotlin/library-tests/java-map-methods/test.kt

@@ -1,3 +1,7 @@
 fun test(m: Map<Int, Int>) = m.getOrDefault(1, 2)
 
 fun test2(s: String) = s.length
+
+fun remove(l: MutableList<Int>) {
+    l.remove(5)
+}