[FIR] Implement FUNCTION_EXPECTED

compiler/testData/diagnostics/tests/extensions/kt1875.fir.kt

@@ -14,7 +14,7 @@ fun test(t: T) {
 }
 
 fun test1(t: T?) {
-    t.<!UNRESOLVED_REFERENCE!>f<!>(1) // todo resolve f as value and report UNSAFE_CALL
+    t.<!FUNCTION_EXPECTED!>f<!>(1) // todo resolve f as value and report UNSAFE_CALL
     t?.<!UNSAFE_IMPLICIT_INVOKE_CALL!>f<!>(1)
     t<!UNSAFE_CALL!>.<!>f?.invoke(1)
     t?.f?.invoke(1)

compiler/testData/diagnostics/tests/extensions/throwOutCandidatesByReceiver.fir.kt

@@ -34,7 +34,7 @@ fun test4() {
 // should be an error on receiver, shouldn't be thrown away
 
 fun test5() {
-    1.(<!UNRESOLVED_REFERENCE!>fun String.()=1<!>)()
+    1.(<!FUNCTION_EXPECTED!>fun String.()=1<!>)()
 }
 
 fun <R: Any> R?.sure() : R = this!!