Provide clear guidance regarding version of decorators-transforms to use

[mike-north]

As of this moment, the latest version of @ember-decorators/babel-transforms is 5.1.4 (stage-2) and the octane blueprint consumes version ^2 (stage-1).

Given that nearly all consumers of this library are unlikely to even know that multiple manifestations of decorators have been proposed, we need to provide some incredibly clear guidance and feedback around what to use.

Most consumers are likely to assume they should use the latest version of everything, and that will lead them down a problematic path in this case. I've tested this hypothesis w/ 4 developers and pointed them to the relevant documentation -- they all ended up getting into trouble and being unable to figure out where to look for solutions.

[buschtoens]

Fixed by #415? 😊

[rwjblue]

In addition to making it possible to know whats going on (#415 does a good job of that), I think we can do a better job of choosing the version of @ember-decorators/babel-transforms in the main ember-decorators blueprint. This will go a long way towards making the onboarding experience less error prone (but doesn't help the "dependency bot problem").

Specifically, I think we can detect the Ember version and if the EMBER_NATIVE_DECORATORS flag is enabled and change the version of @ember-decorators/babel-transforms to install here

ember-decorators/packages/-ember-decorators/blueprints/ember-decorators/index.js

Lines 73 to 75 in 05c782d

	name: '@ember-decorators/babel-transforms',
	target: '^3.1.0'
	});

[buschtoens]

Couldn't we instead release a new version of @ember-decorators/babel-transforms, that actually supports both stage 1 and stage 2? The transform itself already does support both versions via { legacy: true } and we could default this setting to EMBER_NATIVE_DECORATORS.

[rwjblue]

Yep! Probably would work just fine...