Migrate boxInline tests to new multi-file framework

compiler/testData/codegen/boxInline/special/identityCheck.kt

@@ -0,0 +1,33 @@
+// FILE: 1.kt
+
+package test
+
+inline fun <T> doSmth(a: T) : Boolean {
+    return a === a
+}
+
+// FILE: 2.kt
+
+import test.*
+
+fun test1(s: Long): Boolean {
+    return doSmth(s)
+}
+
+fun test2(s: Int): Boolean {
+    return doSmth(s)
+}
+
+inline fun <T> test3(s: T): Boolean {
+    return doSmth(s)
+}
+
+fun box(): String {
+    if (!test1(11111.toLong())) return "fail 1"
+    if (!test2(11111)) return "fail 2"
+    if (!test3(11111)) return "fail 3.1"
+    if (!test3("11111")) return "fail 3.2"
+    if (!test3(11111.3)) return "fail 3.3"
+
+    return "OK"
+}