UX: Uniform focus styles for composer inputs/textarea (PR #10296)

Introduces a uniform indicator of focus for all editable items in the composer (inputs, select kit, textarea), see screenshots for before/after comparisons.

Title field focus when creating a new topic focus-title

Textarea focus (the “Before” screenshot is focused on the textarea, but there is no indicator of focus) focus-textarea

Notice the double border/outline in the before state, replaced with border color change only after focus-selectkit

This PR also disables a default iOS style that looks like flash of background color when setting focus on inputs/textareas.

GitHub

Feel free to merge first thing when you start your day, looks like a really nice change.

Also be sure to try on firefox in case there are unwanted side effects.