Migrate boxInline tests to new multi-file framework

compiler/testData/codegen/boxInline/callableReference/intrinsic.kt

@@ -0,0 +1,15 @@
+// FILE: 1.kt
+
+package test
+
+inline fun call(p: String, s: String.() -> Int): Int {
+    return p.s()
+}
+
+// FILE: 2.kt
+
+import test.*
+
+fun box() : String {
+    return if (call("123", String::length) == 3) "OK" else "fail"
+}