PSI2IR KT-41284 use getters for open data class property values

'allopen' compiler plug-in can make data classes and their members open,
which is a compilation error in usual case, but makes sense for Spring
and other frameworks that generate proxy-classes.

compiler/testData/codegen/bytecodeText/properties/dataClass.kt

@@ -0,0 +1,8 @@
+data class Test(
+    val x: String,
+    val y: String
+)
+
+// 7 GETFIELD Test\.x
+// 7 GETFIELD Test\.y
+// - get, componentN, copy$default, toString, hashCode, 2 times in equals

compiler/testData/codegen/bytecodeText/properties/openDataClass.kt

@@ -0,0 +1,14 @@
+// This test emulates 'allopen' compiler plugin.
+
+@Suppress("INCOMPATIBLE_MODIFIERS")
+open data class Test(
+    open val x: String,
+    open val y: String
+)
+
+// 1 GETFIELD Test\.x
+// 1 GETFIELD Test\.y
+
+// 6 INVOKEVIRTUAL Test\.getX
+// 6 INVOKEVIRTUAL Test\.getY
+// - componentN, copy$default, toString, hashCode, 2 times in equals