_globals._extensions form elements incorrectly rendered

[danielghost]

In addition to #2691, the UI for child nodes are incorrectly displayed in the UI. _components and _extensions are nested under 'Accessibility' (_accessibility) rather than within their own nodes.

[simondate]

I built upon @taylortom 's PR to add titles to the Components and Extensions attributes #2692

Note - I've hardcoded the titles. I tried to use origin.l10n.t('app.components') but it didn't compile, I guess this call is happening too late in the build cycle. I noticed the es.json file didn't have different terms for Components and Extensions and since this is meant to be a quick final fix for the final 0.X.X version I figured this will be acceptable