Make complete tasks in product discovery non clickable

[MAILPOET-4827]

mailpoet/assets/css/src/components-homepage/_product-discovery.scss

@@ -34,6 +34,14 @@
   }
 }
 
+.mailpoet-product-discovery__task--completed {
+  cursor: inherit;
+
+  &:hover {
+    box-shadow: none;
+  }
+}
+
 .mailpoet-product-discovery__task-content {
   h3 {
     color: var(--wp-admin-theme-color);

mailpoet/assets/js/src/homepage/components/discovery-task.tsx

@@ -1,6 +1,7 @@
 import { Icon } from '@wordpress/components';
 import { check } from '@wordpress/icons';
 import { MailPoet } from 'mailpoet';
+import classnames from 'classnames';
 
 type Props = {
   title: string;
@@ -33,11 +34,15 @@ export function DiscoveryTask({
   };
   return (
     <li
-      className="mailpoet-product-discovery__task"
+      className={classnames('mailpoet-product-discovery__task', {
+        'mailpoet-product-discovery__task--completed': isDone,
+      })}
       role="row"
-      onClick={handleTaskClick}
-      tabIndex={0}
-      onKeyDown={(e) => e.key === 'Enter' && handleTaskClick()}
+      onClick={isDone ? undefined : handleTaskClick}
+      tabIndex={isDone ? undefined : 0}
+      onKeyDown={
+        isDone ? undefined : (e) => e.key === 'Enter' && handleTaskClick()
+      }
     >
       <img src={imgSrc} alt={title} width={124} height={72} />
       <div className="mailpoet-product-discovery__task-content">