Render the descriptor in "cannot infer visibility" message

Otherwise it's unclear what member is problematic if it's a fake override
(because the diagnostic in that case is reported on the whole class)

idea/testData/diagnosticMessage/cannotInferVisibility.kt

@@ -0,0 +1,12 @@
+// !DIAGNOSTICS_NUMBER: 1
+// !DIAGNOSTICS: CANNOT_INFER_VISIBILITY
+
+trait T {
+    internal val foo: String
+}
+
+trait U {
+    protected val foo: String
+}
+
+trait V : T, U