Delegation is only allowed if the target type is a trait

idea/testData/checkerWithErrorTypes/quick/DelegationNotTotrait.jet

@@ -0,0 +1,13 @@
+open class Foo() {
+
+}
+
+class Barrr() : <!DELEGATION_NOT_TO_TRAIT!>Foo<!> by Foo() {}
+
+trait T {}
+
+class Br(t : T) : T by t {}
+
+open enum class E() {}
+
+class Test2(e : E) : <!DELEGATION_NOT_TO_TRAIT!>E<!> by e {}