Feature: Donation details overview backend

[alaca]

Description

This PR adds donation details overview backend.

Pre-review Checklist

• Acceptance criteria satisfied and marked in related issue
• Relevant @unreleased tags included in DocBlocks
• Includes unit tests
• Reviewed by the designer (if follows a design)
• Self Review of code and UX completed

[glaubersilva]

@alaca Nice work! I left a few comments with some suggestions.

Also, should we implement the update_item endpoint on this PR as well? I'm asking because I'm not sure if we need it for now.

[glaubersilva]

Not super imortant, but since the includeSensitiveData and anonymousDonations params are the same for get_item and get_items, we can create a getSharedParams to not repeat our selves so we can merge it and both args entries.

Sample: https://github.com/impress-org/givewp/blob/develop/src/API/REST/V3/Routes/Donors/DonorController.php#L46

[alaca]

Yeah, nice idea. I would do that if we had more parameters, but since there are only 2, I think it is much cleaner this way.

[glaubersilva]

@alaca Nice work! I just left a comment about a minor thing.

About the failing unit tests, maybe it can help:

givewp/tests/Unit/API/REST/V3/Routes/Donors/DonorRouteGetCollectionTest.php

Lines 60 to 61 in 1c175ed

	// Remove additional property add by the prepare_response_for_collection() method
	unset($data[0]['_links']);

Another thing to keep in mind is this limitation related to the $response->get_data() method:

givewp/tests/Unit/API/REST/V3/Routes/Donors/DonorRouteGetTest.php

Lines 144 to 145 in 1c175ed

	//The $response->get_data() method do not include _embedded data
	$data = $this->responseToData($response, true);

[alaca]

@glaubersilva, your help and insight on the WP REST API helped me greatly. Thanks, man. Appreciate that.