Merge boxMultiFile testData into box, delete BoxMultiFile test

compiler/testData/codegen/box/multifileClasses/callsToMultifileClassFromOtherPackage.kt

@@ -0,0 +1,24 @@
+// WITH_RUNTIME
+// FILE: 1.kt
+
+import a.*
+
+fun box(): String {
+    if (foo() != "OK") return "Fail function"
+    if (constOK != "OK") return "Fail const"
+    if (valOK != "OK") return "Fail val"
+    varOK = "OK"
+    if (varOK != "OK") return "Fail var"
+
+    return "OK"
+}
+
+// FILE: 2.kt
+
+@file:[JvmName("MultifileClass") JvmMultifileClass]
+package a
+
+fun foo(): String = "OK"
+const val constOK: String = "OK"
+val valOK: String = "OK"
+var varOK: String = "Hmmm?"