chore: Replacing Plugin Updater Service (#341)

* Replaced old updater service with the new WPE Updater service. fixes  #337

* Fixed PHPStan issues

* PHPCS fixes

.changeset/witty-falcons-type.md

@@ -0,0 +1,6 @@
+---
+"@wpengine/wp-graphql-content-blocks": minor
+---
+
+Replaced old plugin service to use the WPE updater service for checking for updates. The new API endpoint will be https://wpe-plugin-updates.wpengine.com/wp-graphql-content-blocks/info.json
+

includes/Updates/CheckForUpgrades.php

@@ -0,0 +1,27 @@
+<?php
+/**
+ * Plugin upgrade checker
+ *
+ * @package WPGraphQL\ContentBlocks\Updates
+ */
+
+declare(strict_types=1);
+
+namespace WPGraphQL\ContentBlocks\Updates;
+
+if ( ! function_exists( 'wp_graphql_content_blocks_check_for_upgrades' ) ) {
+	/**
+	 * Checks for plugin upgrades
+	 */
+	function wp_graphql_content_blocks_check_for_upgrades(): void {
+		$properties = [
+			'plugin_slug'     => 'wp-graphql-content-blocks',
+			'plugin_basename' => WPGRAPHQL_CONTENT_BLOCKS_PLUGIN_PATH,
+		];
+
+		require_once __DIR__ . '/PluginUpdater.php';
+		new PluginUpdater( $properties );
+	}
+
+	add_action( 'admin_init', __NAMESPACE__ . '\wp_graphql_content_blocks_check_for_upgrades' );
+}