[API PULL] Tweak WP Proxy Response to force the types of the price fields

[puntope]

Changes proposed in this Pull Request:

Context: p1726057670716979/1722414955.111429-slack-C02BB3F30TG

This PR forces the types of price fields (price, regular_price, sale_price) to be strings.

Detailed test instructions:

1. Create a high-priority snippet to force the fields to be integers without checking out this PR

add_filter( 'woocommerce_rest_prepare_product_object', function ( $response, $object, $request ) {
    $response->data['price'] = intval( $response->data['price'] );
    $response->data['regular_price'] = intval( $response->data['regular_price'] );
    $response->data['sale_price'] = intval( $response->data['sale_price'] );

    return $response;
}, 999999, 3);

3. Request GET wp-json/wc/v3/products
4. See the prices as integers
5. Checkout this PR
6. Request GET wp-json/wc/v3/products
7. See prices still as integers
8. Request GET wp-json/wc/v3/products?gla_syncable=1
9. See prices as strings

Additional details:

Changelog entry

Tweak - Adjust WP Proxy Response to force the string type for the price fields

[jorgemd24]

Thanks @puntope for working on this. I tested locally and works as expected so LGTM.

[jorgemd24]

Not related to this PR but the below tests is failing. We will need to look into it:

Automattic\WooCommerce\GoogleListingsAndAds\Tests\Unit\Product\SyncerHooksTest::test_delete_created_product_calls_notify_directly
Expectation failed for method name is "notify" when invoked 1 time(s).
Method was expected to be called 1 times, actually called 0 times.