Use ember-debug-handlers for better deprecation support

[rwjblue]

RFC#65 was implemented behind a feature flag in Ember in emberjs/ember.js#11833, and all deprecations updated to include id and until (tracked in emberjs/ember.js#11835).

I created a polyfill for usage with prior Ember versions (rwjblue/ember-debug-handlers-polyfill) that the inspector can use to make tracking down and managing deprecations much easier.

A couple of ideas:

• hide "non-critical" (ones that are being removed more than two versions from now) deprecations in the deprecations pane (with some sort of toggle to show all)
• allow focusing on a single deprecation, by calling Ember.Debug.registerDeprecationHandler and throwing for the id or deprecation message in question

Thoughts?

[teddyzeenny]

👍 Will work on it for version 1.9.

[RobbieTheWagner]

@rwjblue @teddyzeenny do we still want to do anything here or can we close this?

[RobbieTheWagner]

I think with collapsible deprecations, and the ability to flush deprecations now, we can close this.