"Replace 'if' with elvis operator": don't suggest if val initializer is a complex expression

#KT-35165 Fixed

idea/testData/inspectionsLocal/foldInitializerAndIfToElvis/ComplexExpression.kt

@@ -0,0 +1,12 @@
+// PROBLEM: none
+private fun foo(arg: Any): Int {
+    val x =
+        if (arg is String)
+            (arg.length + 1)
+        else
+            arg.hashCode()
+
+    if (<caret>x == null) return 0
+
+    return x
+}