KT-22274 report warning on labels that can't be referenced

Labels are meaningful only if they can be referenced by 'break',
'continue', or 'return' expressions.

compiler/testData/diagnostics/tests/delegatedProperty/inference/labeledDelegatedExpression.kt

@@ -1,7 +1,7 @@
 import kotlin.reflect.KProperty
 
 class A3 {
-    val a: String by l@ MyProperty()
+    val a: String by <!REDUNDANT_LABEL_WARNING!>l@<!> MyProperty()
 
     class MyProperty<T> {}