Script Loader: Pass startOfWeek setting to @wordpress/date

Allows the block editor to respect the site's Week Starts On setting by defining
`i10n.startOfWeek` when initialising the `@wordpress/date` module.

This is a backport of WordPress/gutenberg#41648.

See #56467.
Props andrewserong.


git-svn-id: https://develop.svn.wordpress.org/trunk@54079 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/script-loader.php

@@ -404,6 +404,7 @@ function wp_default_packages_inline_scripts( $scripts ) {
 							/* translators: %s: Duration. */
 							'past'   => __( '%s ago' ),
 						),
+						'startOfWeek'   => (int) get_option( 'start_of_week', 0 ),
 					),
 					'formats'  => array(
 						/* translators: Time format, see https://www.php.net/manual/datetime.format.php */