feat: add Perfmatters to managed plugins

Adds Perfmatters to our list of managed plugins. Also deletes Perfmatters, SCAIP, and Ads.txt Manager from our list of "supported, but not managed" plugins, since they are in fact managed (SCAIP as of #246 and Ads.txt Manager as of #2639).

includes/class-plugin-manager.php

@@ -179,6 +179,13 @@ public static function get_managed_plugins() {
 				'Download'    => 'wporg',
 				'EditPath'    => 'options-general.php?page=password-protected',
 			],
+			'perfmatters'            => [
+				'Name'        => esc_html__( 'Perfmatters', 'newspack' ),
+				'Description' => esc_html__( 'Perfmatters is a lightweight performance plugin developed to speed up your WordPress site.', 'newspack' ),
+				'Author'      => esc_html__( 'forgemedia', 'newspack' ),
+				'AuthorURI'   => esc_url( 'https://forgemedia.io/' ),
+				'PluginURI'   => esc_url( 'https://perfmatters.io/' ),
+			],
 			'publish-to-apple-news'         => [
 				'Name'        => esc_html__( 'Publish to Apple News', 'newspack' ),
 				'Description' => esc_html__( 'Export and synchronize posts to Apple format', 'newspack' ),
@@ -398,11 +405,8 @@ private static function get_supported_plugins_slugs() {
 			'gravityformspolls',
 			'gravityformsmailchimp',
 			'gravityformsstripe',
-			'perfmatters',
 			'onesignal-free-web-push-notifications',
-			'super-cool-ad-inserter-plugin',
 			'web-stories',
-			'ads-txt',
 			'woocommerce-memberships',
 		];
 	}