Code Modernization: Explicitly declare all properties in WP_Test_Stream.

Dynamic (non-explicitly declared) properties are deprecated as of PHP 8.2 and are expected to become a fatal error in PHP 9.0.

The `WP_Test_Stream` class is a stream wrapper for use in the tests and must comply with the PHP requirements for such stream wrappers.

In this case, the class did not declare the required public `$context` property, which led to deprecation notices about the property being dynamically created from the `Tests_Image_Editor_Imagick::test_streams()` and `Tests_Image_Meta::test_stream()` tests.

Reference: [https://www.php.net/manual/en/class.streamwrapper.php#streamwrapper.props PHP Manual: streamWrapper: Properties].

Follow-up to [49230], [50771], [53557], [53558], [53850], [53851], [53852], [53853], [53854], [53856], [53916], [53935], [53936], [53937], [53938], [53942], [53945], [53948].

Props jrf, antonvlasenko.
See #56033.
Built from https://develop.svn.wordpress.org/trunk@53949


git-svn-id: http://core.svn.wordpress.org/trunk@53508 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.1-alpha-53948';
+$wp_version = '6.1-alpha-53949';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.