Improve: add more cases for MoveVariableDeclarationIntoWhen

#KT-30499 Fixed

idea/testData/inspectionsLocal/moveVariableDeclarationIntoWhen/notApplicableInBinaryExpression.kt

@@ -0,0 +1,10 @@
+// PROBLEM: none
+fun test() = true
+
+fun foo(): Int {
+    val a<caret> = test()
+    return null ?: when (a) {
+        true -> 42
+        else -> 5
+    }
+}