[FIR] Disallow qualified access to uninitialized fields in delegate

When using a field as the delegate for a super-interface of an object,
make sure uninitialized fields are not allowed. Specifically, disallow
access to these fields when referenced via object qualifier.

^KT-56489 Fixed

compiler/testData/diagnostics/tests/controlFlowAnalysis/fieldAsClassDelegate.kt

@@ -1,5 +1,6 @@
-// See KT-15566
+// WITH_STDLIB
 // NI_EXPECTED_FILE
+// ISSUE: KT-15566, KT-56489
 
 import DefaultHttpClient.client
 
@@ -22,15 +23,10 @@ object DefaultHttpClientWithFun : HttpClient by fClient() {
 
 private fun fClient() = HttpClientImpl()
 
-private fun <T> lazy(init: () -> T): kotlin.<!UNRESOLVED_REFERENCE!>Lazy<!><T> {
-    init()
-    null!!
-}
-
 object DefaultHttpClientWithBy : HttpClient by client {
     val client by lazy { HttpClientImpl() }
 }
 
 object DefaultFqHttpClient : HttpClient by DefaultFqHttpClient.<!UNINITIALIZED_VARIABLE!>client<!> {
     val client = HttpClientImpl()
-}
+}