Deprecate + Remove Ember Data Functionality

[rwjblue]

As of emberjs/data#6077, ember-data will no longer depend on ember-fetch directly (but will continue to use it if it is present).

We should deprecate usage of all code in addon/ except addon/ajax.ts (since it provides functionality for the ember-data adapter mixin, which will not be required as of ember-data@3.10+ and possibly ember-data@3.9.2).

[rwjblue]

/cc @nlfurniss @xg-wang for visibility

[xg-wang]

@rwjblue Does it makes sense to add deprecation when next ember-data LTS version (3.12) comes out then major bump to remove utils?

[rwjblue]

ember-data@3.9.2 was released dropping the dependency on ember-fetch (with some more tweaks coming in a 3.9.3).

[rwjblue]

Does it makes sense to add deprecation when next ember-data LTS version (3.12) comes out then major bump to remove utils?

I don't think we have to be terribly concerned with the timing here; its probably fine to deprecate whenever we have the time...

[nlfurniss]

I should have chimed in earlier, sorry.

The utils are useful helpers in constructing one-off ajax requests using ember-fetch, so I'm concerned about deprecating them

[xg-wang]

@rwjblue @nlfurniss These utils are private in ember-data. How's your opinion on keeping them in ember-fetch and let ember-data depends/rollsup these?

[rwjblue]

ember-data should definitely not depend on this addon (that was the reason for my work in ember-data for 3.10.1).