Deprecate Index::add_api_key for Client::add_api_key

[julienbourdeau]

Same as algolia/algoliasearch-client-php#378

All keys should be managed using the Client class.

If you use the Index class, you'll attached the key to the index internally. They are not displayed in the dashboard and cannot be retrieve with client::list_api_keys. This is a deprecated feature, that shouldn't be used anymore.

Instead, you can create a key using client::add_api_key that will be attached to the Application internally. You can add restriction on the index to achieve the same behavior.

Other methods like get, update, delete, list are still required to access your existing keys.

[coveralls]

Coverage remained the same at 93.757% when pulling 3cf27ea on fix/deprecate-index-add-keys into 60aec1d on master.

[coveralls]

Coverage remained the same at 93.757% when pulling 3cf27ea on fix/deprecate-index-add-keys into 60aec1d on master.

[raphi]

@julienbourdeau the goal here is just to mark it as deprecated in the doc right?

We could also add deprecation warnings whenever the method is called, WDYT?

[julienbourdeau]

Yes, I checked the lib and it seems like the only thing we do so far for deprecation is to write it in the comment.

Also, we're reconsidering, and we'll probably depredcated all other method (like update, delete, get,...).

[aseure]

Closed in favor of #286