Add MultiFileHighlightingTest which checks that other files are not parsed during highlighting

idea/testData/multiFileHighlighting/dependencies/delegates.kt

@@ -0,0 +1,12 @@
+package delegates
+
+import util.*
+
+class D(val t: T, val t2: T2): T by t, T2 by t2 {
+    fun anotherFun() {
+    }
+}
+
+class WithDelegatedProperty() {
+    val i: Int by someInvalidCode
+}