Enhance/ajax trait

[sapayth]

This trait will reduce some repetitive tasks while registering WordPress AJAX actions.
Example of use:

use WeDevs\WpUtils\AjaxTrait;

class MyAjaxClass {

    use AjaxTrait;

    public function __construct() {
        // Register an AJAX action.
        // This will produce:
        // add_action( 'wp_ajax_yourproject_submit_form, [ $this, 'submit_form_callback' ] );
        // add_action( 'wp_ajax_nopriv_yourproject_submit_form, [ $this, 'submit_form_callback' ] );
        $this->register_ajax( 'yourproject_submit_form', [ $this, 'submit_form_callback' ] );
        $this->register_ajax( 'yourproject_approve_member', 'action_callback', $this->logged_in_only );` // for logged-in users only
        $this->register_ajax( 'yourproject_member_registration', 'action_callback', $this->logged_out_only);` // for logged-out users only
    }
}