minor #42117 [String] Add types to private properties (derrabus)

This PR was merged into the 6.0 branch.

Discussion
----------

[String] Add types to private properties

| Q             | A
| ------------- | ---
| Branch?       | 6.0
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | N/A
| License       | MIT
| Doc PR        | N/A

Commits
-------

1eac94f8cf [String] Add types to private properties

Author: nicolas-grekas

LazyString.php

@@ -18,7 +18,7 @@
  */
 class LazyString implements \Stringable, \JsonSerializable
 {
-    private $value;
+    private \Closure|string $value;
 
     /**
      * @param callable|array $callback A callable or a [Closure, method] lazy-callable

Resources/WcswidthDataGenerator.php

@@ -14,15 +14,15 @@
 use Symfony\Component\HttpClient\HttpClient;
 use Symfony\Component\String\Exception\RuntimeException;
 use Symfony\Component\VarExporter\VarExporter;
+use Symfony\Contracts\HttpClient\HttpClientInterface;
 
 /**
  * @internal
  */
 final class WcswidthDataGenerator
 {
-    private $outDir;
-
-    private $client;
+    private string $outDir;
+    private HttpClientInterface $client;
 
     public function __construct(string $outDir)
     {

Slugger/AsciiSlugger.php

@@ -54,8 +54,8 @@ class AsciiSlugger implements SluggerInterface, LocaleAwareInterface
         'zh' => 'Han-Latin',
     ];
 
-    private $defaultLocale;
-    private $symbolsMap = [
+    private ?string $defaultLocale;
+    private \Closure|array $symbolsMap = [
         'en' => ['@' => 'at', '&' => 'and'],
     ];
 
@@ -64,7 +64,7 @@ class AsciiSlugger implements SluggerInterface, LocaleAwareInterface
      *
      * @var \Transliterator[]
      */
-    private $transliterators = [];
+    private array $transliterators = [];
 
     public function __construct(string $defaultLocale = null, array|\Closure $symbolsMap = null)
     {