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

inc/builders/block-editor/class-block-editor-widget-manager.php

@@ -64,7 +64,7 @@ class Block_Editor_Widget_Manager {
 	 */
 	public function is_block_preview($is_preview) {
 
-		if (defined('REST_REQUEST') && true === REST_REQUEST && 'edit' === filter_input(INPUT_GET, 'context', FILTER_SANITIZE_STRING)) {
+		if (defined('REST_REQUEST') && true === REST_REQUEST && ! empty($_GET['context']) && 'edit' === $_GET['context']) { // phpcs:ignore WordPress.Security.NonceVerification
 			$is_preview = true;
 		}