`discourse-common` was created in the past to share logic between the
'wizard' app and the main 'discourse' app. Since then, the wizard has
been consolidated into the main app, so the separation of
`discourse-common` is no longer useful.
This commit moves `discourse-common/helpers/*` into
`discourse/helpers/*`, removes `discourse-common` from the Ember
resolver config, and adds shims for the imports.
Dismissing admin notices is an admin-only action. This is enforced on the back-end both by a routing constraint and a policy in the relevant service.
However, we still unconditionally display the "Dismiss" button to anyone with access to the admin dashboard. When clicked, it results in a 404 modal (due to the routing constraint.)
With this change we only render the dismiss button for admins.
his is a new feature that lets admins dismiss notices from the dashboard. This helps with self-service in cases where a notice is "stuck", while we work on provisions to prevent "sticking" in the first place.
