[BUGFIX beta] Include package name in deprecation error message

[tben]

So this slightly changes the deprecation message to allow for package (namespace) to be included in the error message. This make it so that the message "will be removed in ember (package version)" is replaced with "will be removed in (package name) (package version)".

This change was proposed because of this usage: https://github.com/adopted-ember-addons/ember-metrics/blob/f604272de70e44ac731c711cfad5eae8792ee3ca/addon/metrics-adapters/google-tag-manager.js#L50

and this issue:
adopted-ember-addons/ember-metrics#453

[bertdeblock]

Seems like a nice improvement! Though AFAIK, every deprecation needs a for value, even the ones triggered by ember-source. So I don't think the 'Ember' fallback will ever be applied and you could write:

message = message + ` This will be removed in ${options.for} ${options.until}.`;

[tben]

I did see that while changing the line. I just wanted to keep the same logic as previously set.

In theory, I could also remove some of if statement as they are a bit useless now with the asserts. However, I figured maybe they had a reason to be there.

[bertdeblock]

AFAICT, 'Ember' should not have been hardcoded there in the first place.
The util is public API that can be used by any addon. Even without for being required, it would be wrong in most cases.
Therefore, I don't think it makes sense to keep the fallback.