+ native classes
+ tracked properties
- Ember.Object
- Ember.Evented
- observers
- mixins
- computed/discourseComputed
Also removes unused wizard infrastructure for warnings. It appears
that once upon on time, either the server can generate warnings,
or some client code can generate them, which requires an extra
confirmation from the user before they can continue to the next step.
This code is not tested and appears unused and defunct. Nothing
generates such warning and the server does not serialize them.
Extracted from https://github.com/discourse/discourse/pull/23678
Previously, we had a `showFooter` boolean on the application controller which would be set true/false in various routes by different routes/controllers. A global `routeWillChange` hook would set it `false` before every route transition, and the destination route/controller would have to set it `true` for the footer to show correctly.
This commit replaces that with a new 'declarative' system. Instead of having to set the value true/false manually, UIs which need the footer to be hidden can simply include the `{{hide-application-footer}}` helper in their template when needed. The helper/service will automatically keep track of all the current invocations of that helper, and only show the footer when there are 0 invocations.
This significantly simplifies things, and removes the need for many observers and controller injections, both of which are considered 'code smells' in modern Ember applications.
