[FIR DFA] Don't consider anonymous object as stable initializer to bind

#KT-43332 Fixed

compiler/fir/analysis-tests/testData/resolve/problems/questionableSmartCast.kt

@@ -0,0 +1,14 @@
+interface A
+interface B
+
+fun foo(x: A) {}
+fun foo(x: B) {}
+
+open class C : A, B
+
+fun main(a: A) {
+    foo(a)
+
+    val anonymousA: A = object : C() {}
+    foo(anonymousA)
+}

compiler/fir/analysis-tests/testData/resolve/problems/questionableSmartCast.txt

@@ -0,0 +1,26 @@
+FILE: questionableSmartCast.kt
+    public abstract interface A : R|kotlin/Any| {
+    }
+    public abstract interface B : R|kotlin/Any| {
+    }
+    public final fun foo(x: R|A|): R|kotlin/Unit| {
+    }
+    public final fun foo(x: R|B|): R|kotlin/Unit| {
+    }
+    public open class C : R|A|, R|B| {
+        public constructor(): R|C| {
+            super<R|kotlin/Any|>()
+        }
+
+    }
+    public final fun main(a: R|A|): R|kotlin/Unit| {
+        R|/foo|(R|<local>/a|)
+        lval anonymousA: R|A| = object : R|C| {
+            private constructor(): R|<anonymous>| {
+                super<R|C|>()
+            }
+
+        }
+
+        R|/foo|(R|<local>/anonymousA|)
+    }