Add default as prop to PluginMoreMenuItem component

[AnthonyLedesma]

closes #39474

What?

This PR resolves the issue reported in #37474 by providing a default as prop of the MenuItem component. This solution allows users to continue to override the as prop just as behavior was previously.

Why?

By being able to use the MenuItem we gain the benefits of existing work done to handle aria attributes for example among other benefits such as styling consistency.

How?

Minimal JavaScript changes to this package. Should only affect custom menu elements in the editor.

Testing Instructions

With this PR the following snippet will render a MenuItem as explained in the PluginMoreMenuItem docs

import { PluginMoreMenuItem } from '@wordpress/edit-post';

...
	return (
		<>
			<PluginMoreMenuItem  onClick={ openModal }>
				{ __( 'Editor settings', 'coblocks' ) }
			</PluginMoreMenuItem>
			...
		</>
        )

Screenshots or screencast

[talldan]

This makes sense to me, thanks for the PR.

There is also a PluginMoreMenuItem in the edit-site package:
https://github.com/WordPress/gutenberg/blob/trunk/packages/edit-site/src/components/header/plugin-more-menu-item/index.js

It would be great to make that consistent before we merge this.

[AnthonyLedesma]

There is also a PluginMoreMenuItem in the edit-site package:
https://github.com/WordPress/gutenberg/blob/trunk/packages/edit-site/src/components/header/plugin-more-menu-item/index.js

I went ahead and pushed the update to the edit-site package as well.

[talldan]

Thanks for fixing this 🎉

[gziolo]

Great fix, thank you 🙇🏻