Return settings prop as object in the REST API

[puntope]

Changes proposed in this Pull Request:

Ref: p1724235667349019/1722414955.111429-slack-C02BB3F30TG

Reverts #2519

This PR fixes an error introduced in #2519

At first, I understood that it was expected to get all empty props as an empty object. However, what was expected was only to get the Settings prop as an object. Rest of the props should be as before.

This PR reverts #2519 and makes only settings to be returned as an object.

Screenshots:

Detailed test instructions:

1. Checkout this PR and
2. Request wp-json/wc/v3/products?gla_syncable=1
3. attributes field is shown as an array (when is empty and when is filled)
4. gla_attributes field is shown as an object (when is empty and when is filled)
5. Request wp-json/wc/v3/settings/general?gla_syncable=1
6. settings field is shown as an object (when is empty and when is filled)
7. Add the following filter which will return empty settings for the flat shipping rate:

add_filter(
	'woocommerce_shipping_instance_form_fields_flat_rate',
	function ( $defaults ) {
		return [];
	},
	10,
	1
);

6. Make a request to v3/shipping/zones/YOUR_SHIPPING_ZONE/methods?gla_syncable=1 which includes a Flat Rate method.
7. See the response:

Before:

After

Additional details:

Changelog entry

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.0%. Comparing base (4c96cd7) to head (9981934).
Report is 19 commits behind head on develop.

Additional details and impacted files

@@            Coverage Diff            @@
##             develop   #2560   +/-   ##
=========================================
  Coverage       65.0%   65.0%           
- Complexity      4588    4591    +3     
=========================================
  Files            475     475           
  Lines          17900   17907    +7     
=========================================
+ Hits           11640   11646    +6     
- Misses          6260    6261    +1     

Flag	Coverage Δ
php-unit-tests	65.0% <100.0%> (+<0.1%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
src/Integration/WPCOMProxy.php	74.1% <100.0%> (ø)

... and 2 files with indirect coverage changes

[jorgemd24]

Thanks, @puntope, for fixing this! However, I noticed there was some confusion—the issue wasn’t actually with the wp-json/wc/v3/settings/general endpoint but with the settings in shipping/zones/X/methods. See this comment: p1724749602301079/1722414955.111429-slack-C02BB3F30TG. I just realized the testing steps hadn’t been updated and still mentioned the settings endpoint, so I’ve updated them. I’ve updated the PR to fix the issue specifically for the shipping zone method endpoint, rather than for all settings in every response. We’re not sure if other endpoints with the setting key will return an object.

Before:

After:

I’ll go ahead and merge this PR for you.