FIR: Support proper implicit return type computation for local classes

compiler/fir/analysis-tests/testData/resolve/localClasses/implicitInAnonymous.kt

@@ -0,0 +1,16 @@
+private val x = object {
+    fun foo(x: Int) = /* here we have not computed return type for "bar" */bar(x)
+    fun bar(y: Int) = this.hashCode() + y > 0
+
+    val w get() = z
+    val z get() = this.hashCode() == 0
+}
+
+fun useBoolean(b: Boolean) {}
+
+fun main() {
+    useBoolean(x.foo(1))
+    useBoolean(x.bar(2))
+    useBoolean(x.w)
+    useBoolean(x.z)
+}