Migrate boxInline tests to new multi-file framework

compiler/testData/codegen/boxInline/anonymousObject/safeCall.kt

@@ -0,0 +1,24 @@
+// FILE: 1.kt
+
+package test
+
+class W(val value: Any)
+
+inline fun W.safe(crossinline body : Any.() -> Unit) {
+    {
+        this.value?.body()
+    }()
+}
+
+// FILE: 2.kt
+
+import test.*
+
+fun box(): String {
+    var result = "fail"
+    W("OK").safe {
+        result = this as String
+    }
+
+    return result
+}