Migrate boxInline tests to new multi-file framework

compiler/testData/codegen/boxInline/complexStack/simple2.kt

@@ -0,0 +1,21 @@
+// FILE: 1.kt
+
+package test
+
+inline fun foo(x: String) = x
+
+class A {
+    fun test(s: String) = s
+}
+
+inline fun processRecords(block: (String) -> String): String {
+    return A().test(block(foo("K")))
+}
+
+// FILE: 2.kt
+
+import test.*
+
+fun box(): String {
+    return processRecords { "O" + it }
+}