Add test for companion field declaring type

Author: tamasvajk

java/ql/test/kotlin/library-tests/companion_objects/companion_objects.expected

@@ -1,2 +1,2 @@
-| companion_objects.kt:1:1:6:1 | MyClass | companion_objects.kt:3:5:5:5 | MyClassCompanion | companion_objects.kt:3:5:5:5 | MyClassCompanion | final,public,static |
-| companion_objects.kt:8:1:13:1 | MyInterface | companion_objects.kt:10:5:12:5 | MyInterfaceCompanion | companion_objects.kt:10:5:12:5 | MyInterfaceCompanion | final,public,static |
+| companion_objects.kt:1:1:6:1 | MyClass | companion_objects.kt:3:5:5:5 | MyClassCompanion | companion_objects.kt:3:5:5:5 | MyClassCompanion | companion_objects.kt:3:5:5:5 | MyClassCompanion | final,public,static |
+| companion_objects.kt:8:1:13:1 | MyInterface | companion_objects.kt:10:5:12:5 | MyInterfaceCompanion | companion_objects.kt:10:5:12:5 | MyInterfaceCompanion | companion_objects.kt:10:5:12:5 | MyInterfaceCompanion | final,public,static |

java/ql/test/kotlin/library-tests/companion_objects/companion_objects.ql

@@ -5,4 +5,4 @@ where
   c.fromSource() and
   cco = c.getCompanionObject() and
   f = cco.getInstance()
-select c, f, cco, concat(f.getAModifier().toString(), ",")
+select c, f, cco, f.getDeclaringType(), concat(f.getAModifier().toString(), ",")