Administration: Add function to standardize admin notices.
Add functions wp_get_admin_notice() and wp_admin_notice() to create and output admin notices & tests for usage. New functions accept a message and array of optional arguments. This commit does not implement the functions. Include new filters: wp_admin_notice_args, wp_admin_notice_markup and action: wp_admin_notice.
Props joedolson, costdev, sakibmd, dasnitesh780, sabernhardt.
Fixes #57791.