Migrate boxInline tests to new multi-file framework

compiler/testData/codegen/boxInline/arrayConvention/simpleAccessInClass.kt

@@ -0,0 +1,35 @@
+// FILE: 1.kt
+
+package test
+
+var res = 1
+
+class A {
+
+    inline operator fun Int.get(z: Int, p: Int) = this + z + p
+
+    inline operator fun Int.set(z: Int, p: Int, l: Int) {
+        res = this + z + p + l
+    }
+
+}
+
+// FILE: 2.kt
+
+import test.*
+
+
+fun box(): String {
+
+    with(A()) {
+        val z = 1;
+
+        val p = z[2, 3]
+        if (p != 6) return "fail 1: $p"
+
+        z[2, 3] = p
+        if (res != 12) return "fail 2: $res"
+    }
+
+    return "OK"
+}