Enable the Posts connector on the front end

Post creation and updating that happens through the REST API is not considered to occur in the "admin" even if the request is made from the block editor. Therefore, these events aren't getting logged because the Posts connector is disabled for the frontend. I don't know what the rationale is for disabling it, but by _not_ doing that, post creation gets logged.

Fixes #1250

connectors/class-connector-posts.php

@@ -28,13 +28,6 @@ class Connector_Posts extends Connector {
 		'deleted_post',
 	);
 
-	/**
-	 * Register connector in the WP Frontend
-	 *
-	 * @var bool
-	 */
-	public $register_frontend = false;
-
 	/**
 	 * Return translated connector label
 	 *