This changeset introduces new `wp_required_field_indicator()` and `wp_required_field_message()` helper functions to generate reusable and consistent required field indicator and message. It also implements these functions in various admin screens.
Props sabernhardt, ryokuhi, joedolson, audrasjb, SergeyBiryukov.
Fixes#54394.
Built from https://develop.svn.wordpress.org/trunk@53888
git-svn-id: http://core.svn.wordpress.org/trunk@53447 1a063a9b-81f0-0310-95a4-ce76da25c4cd