Navigation: Support "Navigate/Related Symbol" for expects/actuals

#KT-20952 Fixed

idea/testData/navigation/relatedSymbols/multiModule/fromNestedExpectClassToActuals/common/common.kt

@@ -0,0 +1,8 @@
+package test
+
+expect class Foo {
+    class <caret>Bar
+}
+
+// REF: [js] (in test.Foo).Bar
+// REF: [jvm] (in test.Foo).Bar

idea/testData/navigation/relatedSymbols/multiModule/fromNestedExpectClassToActuals/js/js.kt

@@ -0,0 +1,5 @@
+package test
+
+actual class Foo {
+    actual class Bar
+}

idea/testData/navigation/relatedSymbols/multiModule/fromNestedExpectClassToActuals/jvm/jvm.kt

@@ -0,0 +1,5 @@
+package test
+
+actual class Foo {
+    actual class Bar
+}