Move blackBoxFile() testData to box/ directory

Delete all test methods (and empty test classes), since they'll be
auto-generated

compiler/testData/codegen/properties/accessToPrivateProperty.kt

@@ -1,52 +0,0 @@
-class A {
-    private var foo = 1
-        get() {
-            return 1
-        }
-
-    fun foo() {
-        foo = 5
-        foo
-    }
-}
-
-class B {
-    private val foo = 1
-        get
-
-    fun foo() {
-        foo
-    }
-}
-
-class C {
-    private var foo = 1
-        get
-        set
-
-    fun foo() {
-        foo = 2
-        foo
-    }
-}
-
-class D {
-    private var foo = 1
-        set(i: Int) {
-            foo = i + 1
-        }
-
-    fun foo() {
-        foo = 5
-        foo
-    }
-}
-
-fun box(): String {
-    A().foo()
-    B().foo()
-    C().foo()
-    D().foo()
-    return "OK"
-}
-

compiler/testData/codegen/properties/accessToPrivateSetter.kt

@@ -1,13 +0,0 @@
-class D {
-    var foo = 1
-        private set
-
-    fun foo() {
-        foo = 2
-    }
-}
-
-fun box(): String {
-   D().foo()
-   return "OK"
-}

compiler/testData/codegen/properties/kt2892.kt

@@ -1,16 +0,0 @@
-open class A
-class B : A() {
-    fun foo() = 1
-}
-
-class Test {
-    val a : A = B()
-    private val b : B get() = a as B //'private' is important here
-
-    fun outer() : Int {
-        fun inner() : Int = b.foo() //'no such field error' here
-        return inner()
-    }
-}
-
-fun box() = if (Test().outer() == 1) "OK" else "fail"