Prep Plugin for release on WordPress.org (#23)

* Update translation text domain
* Escape everything that should be escaped.
* Add nonce checks where needed.
* Sanitize all inputs.
* Apply Code style changes across the codebase.
* Correct many deprecation notices.
* Optimize load order of many filters.
* Add Proper Build script
* Use emojii flags
* Fix i18n deprecation  notice for translating too early
* Put all scripts in footer and load async

wp-multisite-waas.php

@@ -3,7 +3,7 @@
  * Plugin Name: WP Multisite WaaS
  * Description: The WordPress Multisite Website as a Service (WaaS) plugin.
  * Plugin URI: https://wpmultisitewaas.org
- * Text Domain: wp-ultimo
+ * Text Domain: wp-multisite-waas
  * Version: 2.3.4
  * Author: WP Multisite Community
  * Author URI: https://github.com/superdav42/wp-multisite-waas
@@ -81,9 +81,9 @@ if ( ! function_exists('WP_Ultimo')) {
 	 * @return WP_Ultimo
 	 * @since 2.0.0
 	 */
-	function WP_Ultimo() { // phpcs:ignore
+	function WP_Ultimo() { // phpcs:ignore WordPress.NamingConventions.ValidFunctionName.FunctionNameInvalid
 		return WP_Ultimo::get_instance();
-	} // end WP_Ultimo;
+	}
 }
 // Initialize and set to global for back-compat
 $GLOBALS['WP_Ultimo'] = WP_Ultimo();