[FIR] Implement FUNCTION_EXPECTED

compiler/testData/diagnostics/tests/smartCasts/variables/ifElseBlockInsideDoWhileWithBreak.fir.kt

@@ -12,5 +12,5 @@ public fun foo(xx: Any): Int {
         y.length
     } while (true)
     // We could have smart cast here but with break it's hard to detect
-    return x.<!UNRESOLVED_REFERENCE!>length<!>()
-}
+    return x.<!FUNCTION_EXPECTED!>length<!>()
+}

compiler/testData/diagnostics/tests/smartCasts/variables/whileTrue.fir.kt

@@ -0,0 +1,13 @@
+fun x(): Boolean { return true }
+
+public fun foo(pp: Any): Int {
+    var p = pp
+    while(true) {
+        (p as String).length
+        if (x()) break
+        p = 42
+    }
+    // Smart cast is NOT possible here
+    // (we could provide it but p = 42 makes it difficult to understand)
+    return p.<!FUNCTION_EXPECTED!>length<!>()
+}

compiler/testData/diagnostics/tests/smartCasts/variables/whileTrue.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 fun x(): Boolean { return true }
 
 public fun foo(pp: Any): Int {
@@ -11,4 +10,4 @@ public fun foo(pp: Any): Int {
     // Smart cast is NOT possible here
     // (we could provide it but p = 42 makes it difficult to understand)
     return p.<!UNRESOLVED_REFERENCE!>length<!>()
-}
+}