Image Editor checking GD directly for rotate support

[DH-Shredder]

The image editor is currently checking imagerotate() directly to decide whether it should enable the rotate buttons.

We should be checking the image editor.

The initial patch is a bit creative because we assume rotate() is a required function with the WP_Image_Editor class.

Got some extra stuff accidentally in initial patch.
22597.2.diff​ is the proper one.

array( 'methods', array( 'rotate' ) ) — this should be 'methods' => array( 'rotate' ), I imagine?

Yes, yes it should have been, thanks.
Now it is​, and has been further/better tested.

Also passes the mime_type for a more correct response, although this requires pulling the mime from the post.

As a second option, 22597.4.diff​​ also passes mime_type through to check for support.

This requires pulling the mime from the post, though.

It is more accurate, however, since you could get in a situation where rotate() is supported by an editor, but the mime type is not (for instance, in the case of a GD install that is sadly lacking of imagerotate() along with a really old Imagick install lacking setIteratorIndex() when trying to rotate a GIF.

Related: #22543

I'm game for 22597.4.diff​.

In 22863:

In wp_image_editor(), use wp_image_editor_supports() to check for rotation capabilities rather than directly checking the existence of the imagerotate function.

In WP_Image_Editor_GD::test(), check for existence of imagerotate if the rotate capability is required.

Props DH-Shredder
fixes #22597