Deprecation warnings with Ember 3.27

[boris-petrov]

All these usages cause Ember 3.27 to trigger deprecation warnings. It would be nice to have those fixed before Ember 4 as otherwise ember-classic-decorator won't be usable with it.

Somewhat related to #63.

[jherdman]

This is currently biting ember-metrics too. We're looking into refactor out our usages of @classic, but it'd be nice to be able to buy a little time.

[rwjblue]

I think you can add something like:

const _Ember = typeof require === 'function' && typeof require.has === 'function' && require.has('ember') ? require('ember') : Ember;

Then update those usages to use _Ember. I think most/all of those things are still available on the ember module's export just fine...

[lucacorti]

This is an issue for at least ember-metrics on 4.x which depends on e-c-d.

[boris-petrov]

This has been fixed by #89.