Improve use of WP Playground CORS proxy (#182)

* Local blueprint needs to explicitly override constant and uses old schema

* Provide correct host

blueprint.local.json

@@ -23,12 +23,18 @@
         "blogdescription": "Explore the Remote Data Blocks plugin in a WordPress Playground"
       }
     },
+    {
+      "step": "defineWpConfigConsts",
+      "consts": {
+        "USE_PLAYGROUND_CORS_PROXY": false
+      }
+    },
     {
       "step": "installPlugin",
       "options": {
         "activate": true
       },
-      "pluginData": {
+      "pluginZipFile": {
         "resource": "wordpress.org/plugins",
         "slug": "query-monitor"
       }

inc/HttpClient/WPRemoteRequestHandler.php

@@ -32,8 +32,14 @@ public function __invoke( RequestInterface $request, array $options ): PromiseIn
 			$url = (string) $request->getUri();
 
 			// If we are running on WordPress Playground, use the provided CORS proxy.
-			if ( defined( 'USE_PLAYGROUND_CORS_PROXY' ) && USE_PLAYGROUND_CORS_PROXY ) {
-				$url = 'https://playground.wordpress.net/cors-proxy.php?' . $url;
+			if ( defined( 'USE_PLAYGROUND_CORS_PROXY' ) && true === USE_PLAYGROUND_CORS_PROXY ) {
+				$new_uri = $request->getUri()
+					->withHost( 'playground.wordpress.net' )
+					->withScheme( 'https' )
+					->withPath( '/cors-proxy.php' )
+					->withQuery( $url );
+				$request = $request->withUri( $new_uri );
+				$url     = (string) $new_uri;
 			}
 
 			$args = [