Remove generated codegen tests, move all testData to box/

A single test file will be generated out of box/ directory

compiler/testData/codegen/box/labels/propertyAccessorFunctionLiteral.kt

@@ -0,0 +1,23 @@
+val Int.getter: Int
+    get() {
+        return {
+            this@getter
+        }.invoke()
+    }
+
+var Int.setter: Int = 1
+    set(i: Int) {
+        $setter = {
+            this@setter
+        }.invoke()
+    }
+
+fun box(): String {
+    val i = 1
+    if (i.getter != 1) return "getter failed"
+
+    i.setter = 2
+    if (i.setter != 1) return "setter failed"
+
+    return "OK"
+}