Refine 'isMoreSpecific' calculation

Choose member with better visibility, it's needed for proper calculation
of types intersection member scope

 #KT-10481 Fixed

compiler/testData/diagnostics/tests/smartCasts/intersectionScope/moreSpecificSetter.kt

@@ -0,0 +1,15 @@
+open class A {
+    open var value: Int = 4
+        protected set
+}
+
+class MutableA : A() {
+    override var value: Int = 4
+        public set
+}
+
+fun test(myA: A) {
+    if (myA is MutableA) {
+        <!DEBUG_INFO_SMARTCAST!>myA<!>.value = 5
+    }
+}