MSD - Stats Card - Handle Success Response

[ashiagr]

Parent wordpress-mobile/WordPress-Android#15749

This is a draft PR that includes the following changes for adding the Stats Card to the cards result:

• JSON deserialization for the success response
• Mapping success response to model

---

There's nothing to test in this PR as the dashboard/cards endpoint doesn't yet include the Stats Card yet. So that existing tests work as expected, I've updated the following test classes:

• CardsRestClientTest is updated to add StatsResponseand cards.json is updated to include the Stats Card.
• CardsStoreTest is updated to add STATS_ENTITY to CARDS_ENTITY.

---

Note: We might want to keep this PR in draft mode until the dashboard/cards endpoint is updated for the Stats Card as the final structure might vary. With the current prod version of the endpoint, the stats card response being null is not added to the cards list.

[zwarm]

We might want to keep this PR in draft mode

@ashiagr , yes, let's do that!
(1) I added comments to the endpoint because it's needed for iOS; not sure if we want to do anything with it.
(2) Let's sync on what the success looks like ... I was basing it off of the following, but that can be changed.

Success: return array(
        'ok'           => true,
	'error'      => '',
	'stats'      => stats data,
      );
Failure: return array(
        'ok'     => false,
	 'error' => 'error message',
      );

NOTE:: We decided against the above approach, this is here for history purposes

[peril-wordpress-mobile]

You can trigger optional UI/connected tests for these changes by visiting CircleCI here.

[zwarm]

@ashiagr - The cards-data endpoint has been deployed - you can swap out the mock data responses.

[zwarm]

@ashiagr Very well done 👏

❤️ for the patience in changing all those tests.

I like the improvement that added "label" to types so the arguments build out works smoothly.

I tested using the WPAndroid#[15893 ](MSD - Handle Single Dashboard Card Error in UI) and was able to view the stats card as expected. I also visited a few web sites and PTR's, and the counts updated.

Please feel free to merge when you feel comfortable.