v2.17.0

Release v2.17.0

release-check: OK c918e3a

Changelog

Icons on area navigation and settings section tabs

Added

• AreaNavItem::$icon and SettingsSection::$icon (optional, last constructor argument): the page header's
  area navigation and the settings scaffold's section tabs pass them to the tabs partial, so a bundle's own tabs
  follow the host's tab style (data-tab-style, 2.16) like any other tab row. Without an icon nothing changes.