This commit introduces a little bit of duplication
since the old plugin UIs not using the new plugin show
page look different from ones like AI and Gamification
which have been converted. We can use the new admin
header component on the plugins list, but for the other
pages we are manually rendering a breadcrumb trail and
the list of plugin tabs.
Over time as we convert more plugins to use the new UI
guidelines and show page we can get rid of this duplication.
A previous refactor has prevented errors to show correctly. The guilt of the issue is that we were not calling the error variable correctly in the templates.
This commit also adds a spec for this case, and removes the need for `I18n.backend.store_translations` in specs so we don't have to write too much boilerplate each time we write a spec.
