Merge branch '5.2' into 5.x

* 5.2:
  [Finder] Fix gitignore regex build with "**"
  Fixed deprecation warnings about passing null as parameter
  [Security] Keep Bulgarian wording consistent across all texts.
  Migrate configuration file for PHP CS Fixer 2.19/3.0
  [Form] Replace broken ServerParams mock
  [Mailer] Fix SES API call with UTF-8 Addresses

Author: fabpot

Cookie.php

@@ -46,7 +46,7 @@ class Cookie
      * Sets a cookie.
      *
      * @param string      $name         The cookie name
-     * @param string      $value        The value of the cookie
+     * @param string|null $value        The value of the cookie
      * @param string|null $expires      The time the cookie expires
      * @param string|null $path         The path on the server in which the cookie will be available on
      * @param string      $domain       The domain that the cookie is available
@@ -62,7 +62,7 @@ public function __construct(string $name, ?string $value, string $expires = null
             $this->rawValue = $value;
         } else {
             $this->value = $value;
-            $this->rawValue = rawurlencode($value);
+            $this->rawValue = rawurlencode($value ?? '');
         }
         $this->name = $name;
         $this->path = empty($path) ? '/' : $path;