Migrate boxInline tests to new multi-file framework

compiler/testData/codegen/boxInline/reified/isCheck/simple.kt

@@ -0,0 +1,35 @@
+// FILE: 1.kt
+
+package test
+
+class A
+class B
+
+inline fun <reified T> Any?.foo() = this is T
+
+// FILE: 2.kt
+
+import test.*
+
+fun box(): String {
+    if (null.foo<Any>() != false) return "fail 1"
+    if (null.foo<Any?>() != true) return "fail 2"
+
+    if (null.foo<A>() != false) return "fail 3"
+    if (null.foo<A?>() != true) return "fail 4"
+
+    val a = A()
+
+    if (a.foo<Any>() != true) return "fail 5"
+    if (a.foo<Any?>() != true) return "fail 6"
+
+    if (a.foo<A>() != true) return "fail 7"
+    if (a.foo<A?>() != true) return "fail 8"
+
+    val b = B()
+
+    if (b.foo<A>() != false) return "fail 9"
+    if (b.foo<A?>() != false) return "fail 10"
+
+    return "OK"
+}