Remove generated codegen tests, move all testData to box/

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

compiler/testData/codegen/box/innerNested/dataLocalVariable.kt

@@ -0,0 +1,6 @@
+fun ok(b: Boolean) = if (b) "OK" else "Fail"
+
+fun box(): String {
+    val data = java.util.Arrays.asList("foo", "bar")!!
+    return ok(data.contains("foo"))
+}