Features should be panned into view on focus

[Malvoz]

Features should be panned into view on focus (similar to how popups are panned into view when opened). Otherwise a failure of WCAG 2.1 SC 2.4.7 Focus Visible.

[Malvoz]

Features outside the view are no longer treated as relevant for tabbing and thus not keyboard focusable (per #596). And I believe there's currently no way for authors to programmatically focus a feature, so this is no longer needed AFAICT.