MoveVariableDeclarationIntoWhenInspection shouldn't report a multi-line variable

#KT-30457 Fixed

idea/testData/inspectionsLocal/moveVariableDeclarationIntoWhen/notApplicableMultyLine.kt

@@ -0,0 +1,11 @@
+// PROBLEM: none
+
+fun foo(): Int {
+    val a<caret> = if (true) true
+    else false
+
+    return when (a) {
+        true -> 42
+        else -> null
+    } ?: 55
+}