Connectors: Respect custom setting_name in connector registration.

`WP_Connector_Registry::register()` always auto-generates the `setting_name`
for connectors with `api_key` authentication, ignoring any caller-provided
value. This prevents connectors from using existing WordPress options as their
API key storage.
This change checks for a non-empty `setting_name` in the provided args before
falling back to the auto-generated name.

Props jorgefilipecosta, gziolo.
Fixes #64957.

git-svn-id: https://develop.svn.wordpress.org/trunk@62116 602fd350-edb4-49c9-b593-d223f7449a82

Author: jorgefilipecosta

src/wp-includes/class-wp-connector-registry.php

@@ -192,7 +192,11 @@ public function register( string $id, array $args ): ?array {
 			if ( ! empty( $args['authentication']['credentials_url'] ) && is_string( $args['authentication']['credentials_url'] ) ) {
 				$connector['authentication']['credentials_url'] = $args['authentication']['credentials_url'];
 			}
-			$connector['authentication']['setting_name'] = 'connectors_ai_' . str_replace( '-', '_', $id ) . '_api_key';
+			if ( ! empty( $args['authentication']['setting_name'] ) && is_string( $args['authentication']['setting_name'] ) ) {
+				$connector['authentication']['setting_name'] = $args['authentication']['setting_name'];
+			} else {
+				$connector['authentication']['setting_name'] = 'connectors_ai_' . str_replace( '-', '_', $id ) . '_api_key';
+			}
 		}
 
 		if ( ! empty( $args['plugin'] ) && is_array( $args['plugin'] ) ) {