FIR checker: fix local type approximation on delegated property

Previously types of delegated property is not approximated, which can
cause local types to leak through public APIs.

compiler/testData/diagnostics/tests/declarationChecks/localObjectInInnerClass.kt

@@ -0,0 +1,30 @@
+interface I1
+interface I2
+
+interface Lazy<T> {
+    operator fun getValue(a1: Any, a2: Any): T
+}
+
+fun <T> lazy(f: () -> T): Lazy<T> = throw Exception()
+
+class A {
+    private inner class B {
+        val o1 = object : I1 {}
+        val o2 by lazy {
+            object : I1 {}
+        }
+        <!AMBIGUOUS_ANONYMOUS_TYPE_INFERRED!>val o3<!> = object : I1, I2 {} // FIR allows this since the containing class is private
+        <!AMBIGUOUS_ANONYMOUS_TYPE_INFERRED!>val o4<!> by lazy { // FIR allows this since the containing class is private
+            object : I1, I2 {}
+        }
+
+        private val privateO1 = object : I1 {}
+        private val privateO2 by lazy {
+            object : I1 {}
+        }
+        private val privateO3 = object : I1, I2 {}
+        private val privateO4 by lazy {
+            object : I1, I2 {}
+        }
+    }
+}