Automatic Minor Updates

Add "Enable automatic minor core updates" (on by default, new Core Updates section): WordPress installs minor core releases — security and maintenance patches — on its own, as soon as they ship, while major and development releases stay manual. Because core is gitignored on our sites, this also stops WordPress treating the site as a version-controlled checkout, which was otherwise blocking every automatic update including per-plugin and per-theme auto-updates. Lockable with the WPH_AUTO_CORE_MINOR_UPDATES constant; the setting notes when AUTOMATIC_UPDATER_DISABLED or DISALLOW_FILE_MODS makes it moot.