[deprecation] Deprecate ScalarValueToConstFetchRector

[TomasVotruba]

Deprecates ScalarValueToConstFetchRector.

The rule subscribes to every String_, Int_ and Float_ node in the project and compares the raw value. There is no context check, so the same value in an unrelated place is replaced too:

 final class SomeClass
 {
     public function run(array $items)
     {
-        $timeout = 10;
+        $timeout = \SomeClass::FOOBAR_INT;

         // unrelated, but replaced as well
-        return array_slice($items, 0, 10);
+        return array_slice($items, 0, \SomeClass::FOOBAR_INT);
     }
 }

The same happens with strings used as array keys, version numbers or messages. There is no way to configure a narrower target, so the rule cannot be made safe by configuration.

Use a custom rule scoped to the exact context (a specific argument, property or method) instead.

The rule now implements DeprecatedInterface and throws in refactor(). The ScalarValueToConstFetch value object is kept, so existing configs still load.