Tests: Move the test for wp_save_image_file() with a GD resource to a more appropriate place.

When passed a GD resource as `$image`, `wp_save_image_file()` should throw a deprecated argument notice:
{{{
Function wp_save_image_file was called with an argument that is deprecated since version 3.5.0!
$image needs to be a WP_Image_Editor object.
}}}

The test verifies that the notice is thrown as expected.

Includes:
* Removing the `Tests_Functions_Deprecated` class. It appears to be initially intended for testing deprecated functions or arguments, but this was later superseded by the `@expectedDeprecated` annotation.
* Removing a redundant test for `wp_save_image_file()` **not** throwing a deprecation notice when passed a `WP_Image_Editor` instance. This is already covered by `test_wp_save_image_file()`, which would fail if there is an unexpected deprecation notice.

Follow-up to [1061/tests], [25408], [25409], [53529].

See #56793.
Built from https://develop.svn.wordpress.org/trunk@55066


git-svn-id: http://core.svn.wordpress.org/trunk@54599 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.2-alpha-55065';
+$wp_version = '6.2-alpha-55066';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.