Minor, move tests about Java field and Kotlin property

Because the `fieldRename` directory was originally about cases when
private fields are renamed because of clashes.

compiler/testData/codegen/box/javaFieldAndKotlinProperty/javaFieldAndKotlinPropertyWithSmartcast.kt

@@ -0,0 +1,27 @@
+// TARGET_BACKEND: JVM_IR
+// IGNORE_BACKEND_K1: JVM_IR
+// IGNORE_BACKEND_K2: JVM_IR
+// tried to access field My.b from class TestKt
+
+// FILE: Jaba.java
+
+public class Jaba {
+    public String a = "O";
+    public String b = "";
+}
+
+// FILE: test.kt
+class My : Jaba() {
+    private val a: String = "FAIL"
+    private val b: String = "FAIL"
+}
+
+fun test(j: Any): String {
+    if (j is My) {
+        j.b = "K"
+        return j.a + j.b
+    }
+    return "NO SMARTCAST"
+}
+
+fun box(): String = test(My())