Change the add_theme_support feature name for wide images

[pyronaur]

Currently to add wide-image support theme developers have to do this:

    add_theme_support(
        'gutenberg',
        array(
            'wide-images' => true,
        )
    );

That should probably be renamed to something like:

add_theme_support('align-wide')
// or
add_theme_support('wide-alignments')

cc @youknowriad, @jasmussen

[youknowriad]

Two reasons behind this:

• Avoid the "gutenberg" code name in production
• The "wide-images" option is not only for images but all blocks supporting wide alignments.

[pyronaur]

Thanks for the clarification 👍

[Luehrsen]

Just to add to the conversation:

There are a lot of cases, where the availability of wide-alignments cannot be set globally. Sometimes we provide extra Page Templates for that functionality, sometimes it's special post types.

So having the ability to narrow availability down would be great.

[maddisondesigns]

I also mentioned something similar in #2823 a few months ago, that it would be a good idea to rename these, as it's confusing that 'adding support' for 'wide-images' also does the same thing for tables as well.