\ before global namespace functions causes an escaping function error.

[GaryJones]

Related to #764.

This method is in a namespaced class:

public function do_footer_nav() {
	echo \wp_kses_post(
		\genesis_get_nav_menu(
			[
				'menu_class'     => 'menu genesis-nav-menu menu-footer',
				'theme_location' => 'footer',
			]
		)
	);
}

The presence of the \ before the function calls from the global namespace, means that an error of Expected next thing to be an escaping function, ... not "\" appears.

I've not looked into the change needed, but if the sniff could allow an optional \ before those function checks, that would be great :-)

Using fully-qualified function calls is faster. Details and benchmarks are here. This is from an inspection from the PHP Inspections extension for PhpStorm.