Build/Test Tools: Expand Slack notifications for GitHub Actions.

This expands Slack notifications to include success, cancelled, and “fixed” GitHub Action workflow run outcomes in addition to failures.

A “fixed” outcome occurs when the previous run for a workflow failed and the current one succeeds. This matches the behavior that was native to TravisCI by setting `on_success` for notifications to `change`.

The message details and where each outcome is posted is controlled by Slack workflows.

The Slack notification logic has also been pulled into a separate workflow to prevent repeating code in every workflow.

See #52644.
Built from https://develop.svn.wordpress.org/trunk@51535


git-svn-id: http://core.svn.wordpress.org/trunk@51146 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-cron.php

@@ -60,7 +60,7 @@ function _get_cron_lock() {
 	global $wpdb;
 
 	$value = 0;
-	if ( wp_using_ext_object_cache() ) {
+	if (wp_using_ext_object_cache()) {
 		/*
 		 * Skip local cache and force re-fetch of doing_cron transient
 		 * in case another process updated the cache.

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.9-alpha-51534';
+$wp_version = '5.9-alpha-51535';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.