Plugins and Themes Auto-Updates: allow overriding of the HTML for the...

Plugins and Themes Auto-Updates: allow overriding of the HTML for the auto-update setting link. This will let plugins show better/specific information when they are overriding the auto-update settings, for example "Updates are managed by ... plugin".

Introduces: `theme_auto_update_setting_html`, `plugin_auto_update_setting_html`, and `theme_auto_update_setting_template` filters.

Props audrasjb, pbiron, azaozz.
Fixes #50280.
Built from https://develop.svn.wordpress.org/trunk@48077


git-svn-id: https://core.svn.wordpress.org/trunk@47844 1a063a9b-81f0-0310-95a4-ce76da25c4cd