Introduce MultiModuleHighlightingTest

Checks that analysis produces expected diagnostics when configured by real IDEA module

idea/testData/multiModuleHighlighting/visibility/m1/m1.kt

@@ -0,0 +1,27 @@
+package m1
+
+public class PublicClassInM1
+class InternalClassInM1
+private class PrivateClassInM1
+
+public fun publicFunInM1() {
+}
+fun internalFunInM1() {
+}
+private fun privateFunInM1() {
+}
+
+fun testVisibility() {
+    <error descr="[UNRESOLVED_REFERENCE] Unresolved reference: ClassInM2">ClassInM2</error>()
+}
+
+public open class A internal () {
+    private fun pri() {
+    }
+    fun int() {
+    }
+    protected fun pro() {
+    }
+    public fun pub() {
+    }
+}