Provide warning if href passed to PluginMoreMenuItem is an incomplete…

[MigdaliaBrito]

… URL fragment identifier (#)

Description

Addresses #12535. Added a console warning if href value being passed to the PluginMoreMenuItem component is a # sign.

How has this been tested?

Paste the following in the console:

( function() {
	const { createElement } = wp.element;
	const { PluginMoreMenuItem } = wp.editPost;
	const { registerPlugin } = wp.plugins;

	registerPlugin( 'my-plugin-more-menu-button', {
		render() {
			return createElement(
				PluginMoreMenuItem,
				{
					href: '#',
				},
				'Test Link'
			);
		},
	} );
} )();

This should trigger the following console warning:
Links should trigger navigation. Replace href value for PluginMoreMenuItem component with a navigable URL.

The above code adds the following link item in the More Items menu

Screenshots

Types of changes

This is just introducing a console warning to encourage accessibility best practices when creating links. This affects the More Options menu.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.

[youknowriad]

Thanks for the contribution @MigdaliaBrito

As I already said on the issue, if we start adding those kind of warnings, we won't stop as we need 10 warnings per component. I won't block the PR but I'm not convinced we should do it.

[gziolo]

I'm also sceptical about introducing this type of checks as part of the production code. If we want to have this kind of logic, we might want to start with linting or something similar. In general, I don't feel like we can prevent all bad use cases and we should try to mitigate it by doing a proper education in documentation explaining how to use this component properly.

[aduth]

As of the merging of #14151, there is now some prior art for how we can discourage invalid component usage at build-time rather than at runtime (it is possible to use these lint rules outside Gutenberg). For that reason, I'd suggest we try to coalesce around this approach to enforcing best practices, and I think #12535 would be an appropriate application of this pattern.