WP 5.3 compatibility: Fix the parameters passed to add_submenu_page()

[afercia]

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Please give us a description of what happened.

Noticed while investigating on #14196

WordPress 5.3 added a $position argument to all these functions:

add_submenu_page()
add_management_page()
add_options_page()
add_theme_page()
add_plugins_page()
add_users_page()
add_dashboard_page()
add_posts_page()
add_media_page()
add_links_page()
add_pages_page()
add_comments_page()

See related WordPress Trac changeset and ticket:
https://core.trac.wordpress.org/changeset/46197
https://core.trac.wordpress.org/ticket/39776

Yoast SEO uses its own methods for the admin menu but in the end it uses add_submenu_page().

$position is now the add_submenu_page() 7th argument. and this is incompatible with the way
the function is used in Yoast SEO, where a 7th parameter isn't actually passed but it's used for a "hook callback". See for example WPSEO_Base_Menu->register_submenu_page() and WPSEO_Base_Menu->get_submenu_page().

wordpress-seo/admin/menu/class-base-menu.php

Lines 170 to 197 in eb1095a

	protected function register_submenu_page( $submenu_page ) {
	$page_title = $submenu_page[2];
	// We cannot use $submenu_page[1] because add-ons define that, so hard-code this value.
	if ( $submenu_page[4] === 'wpseo_licenses' ) {
	$page_title = $this->get_license_page_title();
	}
	$page_title .= ' - Yoast SEO';
	// Force the general manage capability to be used.
	$submenu_page[3] = $this->get_manage_capability();
	// Register submenu page.
	$hook_suffix = add_submenu_page(
	$submenu_page[0],
	$page_title,
	$submenu_page[2],
	$submenu_page[3],
	$submenu_page[4],
	$submenu_page[5]
	);
	// If necessary, add hooks for the submenu page.
	if ( isset( $submenu_page[6] ) && ( is_array( $submenu_page[6] ) ) ) {
	$this->add_page_hooks( $hook_suffix, $submenu_page[6] );
	}
	}

See also this comment on the WordPress Trac follow-up ticket
https://core.trac.wordpress.org/ticket/48599#comment:8