Remove generated codegen tests, move all testData to box/

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

compiler/testData/codegen/box/multiDecl/ValCapturedInLocalFunction.kt

@@ -0,0 +1,13 @@
+class A {
+    fun component1() = 1
+    fun component2() = 2
+}
+
+fun box() : String {
+    val (a, b) = A()
+
+    fun run(): Int {
+        return a
+    }
+    return if (run() == 1 && b == 2) "OK" else "fail"
+}