Fix filter() to use keys and allow extension capabilities

The filter() method had three bugs:

1. array_filter callback received values instead of keys, causing
   TypeError when capability values are arrays (e.g. goog:chromeOptions)

2. Extension capabilities (keys containing ':') were stripped, but
   W3C spec requires them to be allowed through

3. array_values() destroyed the key-value mapping, turning
   {"browserName": "chrome"} into ["chrome"]

Fix by using ARRAY_FILTER_USE_KEY, allowing extension capabilities
per W3C spec, and removing array_values() wrapper.

References:
- https://www.w3.org/TR/webdriver2/#dfn-extension-capability
- https://www.php.net/array_filter

Author: daifma

lib/WebDriver/WebDriver.php

@@ -166,7 +166,7 @@ public function sessions()
      */
     private function filter($capabilities)
     {
-        return $capabilities ? array_values(array_filter($capabilities, function ($capability) { return self::$w3cCapabilities[$capability] ?? 0; })) : null;
+        return $capabilities ? array_filter($capabilities, function ($key) { return isset(self::$w3cCapabilities[$key]) || str_contains($key, ':'); }, ARRAY_FILTER_USE_KEY) : null;
     }
 
     /**