Don't generate unnecessary accessors for private class properties

compiler/testData/codegen/properties/privateClassPropertyAccessors.kt

@@ -0,0 +1,31 @@
+class C {
+    // All these properties should have corresponding accessors
+    private val valWithGet: String
+        get() = ""
+
+    private var varWithGetSet: Int
+        get() = 0
+        set(value) {}
+
+    private var delegated: Int by Delegate
+
+    private var String.extension: String
+        get() = this
+        set(value) {}
+
+    class object {
+        private val classObjectVal: Long
+            get() = 1L
+    }
+
+    // This property should not have accessors
+    private var varNoAccessors = 0L
+        get set
+}
+
+
+object Delegate {
+    fun get(x: C, p: PropertyMetadata) = throw AssertionError()
+
+    fun set(x: C, p: PropertyMetadata, value: Int) = throw AssertionError()
+}