Migrate boxInline tests to new multi-file framework

compiler/testData/codegen/boxInline/complexStack/simple4.kt

@@ -0,0 +1,20 @@
+// FILE: 1.kt
+
+package test
+
+inline fun foo(x: String) = x
+
+fun test(a: String, s: String) = s
+
+
+inline fun processRecords(block: (String, String) -> String): String {
+    return test("stub", block(foo("O"), foo("K")))
+}
+
+// FILE: 2.kt
+
+import test.*
+
+fun box(): String {
+    return processRecords { a, b -> a + b}
+}