Minor: merge HierarchicalExpectActualMatchingTests into MultiplatformHighlightingTests

idea/testData/multiplatform/diamondSeesTwoActuals/bottom/bottom.kt

@@ -0,0 +1,7 @@
+package sample
+
+fun main() {
+    A().foo()
+    // fromLeft should be resolved, because 'left' comes first in dependencies order!
+    A().fromLeft()
+}

idea/testData/multiplatform/diamondSeesTwoActuals/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/multiplatform/diamondSeesTwoActuals/left/left.kt

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

idea/testData/multiplatform/diamondSeesTwoActuals/right/right.kt

@@ -0,0 +1,5 @@
+package sample
+
+actual class A /* Right */ {
+    actual fun foo(): Int = 100500
+}

idea/testData/multiplatform/diamondSeesTwoActuals/top/top.kt

@@ -0,0 +1,5 @@
+package sample
+
+expect class A {
+    fun foo(): Int
+}