Add tests for 'if-when' and 'when' transformations

idea/testData/codeInsight/codeTransformations/branched/when/flatten/flattenWithSubject.kt

@@ -0,0 +1,11 @@
+fun test(n: Int): String {
+    return <caret>when(n) {
+        in 0..10 -> "small"
+        in 10..100 -> "average"
+        else -> when(n) {
+            in 100..1000 -> "big"
+            in 1000..10000 -> "very big"
+            else -> "unknown"
+        }
+    }
+}

idea/testData/codeInsight/codeTransformations/branched/when/flatten/flattenWithSubject.kt.after

@@ -0,0 +1,9 @@
+fun test(n: Int): String {
+    return <caret>when (n) {
+        in 0..10 -> "small"
+        in 10..100 -> "average"
+        in 100..1000 -> "big"
+        in 1000..10000 -> "very big"
+        else -> "unknown"
+    }
+}

idea/testData/codeInsight/codeTransformations/branched/when/flatten/flattenWithUnmatchedSubjects.kt

@@ -0,0 +1,12 @@
+//IS_APPLICABLE: false
+fun test(n: Int): String {
+    return <caret>when(n) {
+        in 0..10 -> "small"
+        in 10..100 -> "average"
+        else -> when {
+            n in 100..1000 -> "big"
+            n in 1000..10000 -> "very big"
+            else -> "unknown"
+        }
+    }
+}

idea/testData/codeInsight/codeTransformations/branched/when/flatten/flattenWithoutSubject.kt

@@ -0,0 +1,11 @@
+fun test(n: Int): String {
+    return <caret>when {
+        n in 0..10 -> "small"
+        n in 10..100 -> "average"
+        else -> when {
+            n in 100..1000 -> "big"
+            n in 1000..10000 -> "very big"
+            else -> "unknown"
+        }
+    }
+}

idea/testData/codeInsight/codeTransformations/branched/when/flatten/flattenWithoutSubject.kt.after

@@ -0,0 +1,9 @@
+fun test(n: Int): String {
+    return <caret>when {
+        n in 0..10 -> "small"
+        n in 10..100 -> "average"
+        n in 100..1000 -> "big"
+        n in 1000..10000 -> "very big"
+        else -> "unknown"
+    }
+}