[Expect/Actual] Add testdata on hierarchical expect/actual matching

idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/diamondDuplicateActuals/bottom/bottom.kt

@@ -0,0 +1,16 @@
+package sample
+
+actual class A {
+    actual fun foo(): Int = 45
+    fun fromBottom(): Int = 0
+}
+
+fun main() {
+    A().foo()
+
+    // Any behaviour is acceptable, as the code is erroneous.
+    // At the time of writing this test, we resolve to nearest A, i.e.
+    //  'fromBottom' is resolved, and 'fromLeft' is not.
+    A().<!UNRESOLVED_REFERENCE("fromLeft")!>fromLeft<!>()
+    A().fromBottom()
+}

idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/diamondDuplicateActuals/dependencies.txt

@@ -0,0 +1,8 @@
+MODULE top { platform=[JVM, JS, Native] }
+MODULE left { platform=[JVM, JS, Native] }
+MODULE right { platform=[JVM, JS, Native] }
+MODULE bottom { platform=[JVM] }
+
+left -> top { kind=DEPENDS_ON }
+right -> top { kind=DEPENDS_ON }
+bottom -> left, right { kind=DEPENDS_ON }

idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/diamondDuplicateActuals/left/left.kt

@@ -0,0 +1,6 @@
+package sample
+
+actual class A /* Left */ {
+    actual fun foo(): Int = 42
+    fun fromLeft(): String = ""
+}

idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/diamondDuplicateActuals/right/right.kt

@@ -0,0 +1 @@
+package sample

idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/diamondDuplicateActuals/top/top.kt

@@ -0,0 +1,5 @@
+package sample
+
+expect class <!AMBIGUOUS_ACTUALS("Class 'A'", "bottom for JVM, left")!>A<!> {
+    fun <!AMBIGUOUS_ACTUALS("Function 'foo'", "bottom for JVM, left")!>foo<!>(): Int
+}