[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)
+}