FoldInitializerAndIfToElvisInspection: don't report when 'var' variable has no explicit type and it's used as not nullable type

#KT-38349 Fixed

idea/testData/inspectionsLocal/foldInitializerAndIfToElvis/VarUsedAsNotNullable.kt

@@ -0,0 +1,8 @@
+// PROBLEM: none
+fun test(foo: Int?, bar: Int): Int {
+    var i = foo
+    <caret>if (i == null) {
+        return bar
+    }
+    return i
+}