Add tests for KT-26141 (yet without changes)

idea/testData/multiModuleHighlighting/multiplatform/sealedTypeAlias/common/common.kt

@@ -0,0 +1,6 @@
+package p
+
+expect sealed class Presence {
+    object Online: Presence
+    object Offline: Presence
+}

idea/testData/multiModuleHighlighting/multiplatform/sealedTypeAlias/jvm/jvm.kt

@@ -0,0 +1,8 @@
+// !CHECK_HIGHLIGHTING
+package p
+
+actual typealias Presence = P
+sealed class P {
+    object Online : P()
+    object Offline : P()
+}