Migrate CompileKotlinAgainstKotlin test to multi-file framework

compiler/testData/compileKotlinAgainstKotlin/simpleValAnonymousObject.kt

@@ -0,0 +1,20 @@
+// FILE: A.kt
+
+package pkg
+
+interface ClassA {
+    companion object {
+        val DEFAULT = object : ClassA {
+            override fun toString() = "OK"
+        }
+    }
+}
+
+// FILE: B.kt
+
+import pkg.ClassA
+
+fun main(args: Array<String>) {
+    val obj = ClassA.DEFAULT
+    obj.toString()
+}