Merged PR 42072: Update Chat Profile controller to use correct interf…

…aces

## What's being changed

We have removed a redundant class `Dotdigitalgroup\Chat\Model\EmailFlagManager`, and we have updated the `Dotdigitalgroup\Chat\Controller\Profile\Index` class to follow Magento best practices.

## Why it's being changed

This resolves some critical issues reported by the Magento upgrade compatibility tool.

## How to review / test this change

1. Enable chat
2. Test chat messaging works as expected.
3. Run DI compile insure there are no missing dependencies within any of the Dotdigital Modules

## Notes
The Flag Manager class was used in the very early days of the Chat codebase, when Chat was provided in the Email module. It provided a way of saving temporary config data during the trial setup. At the time we had to include it in our module in order to support Magento version 2.2 and lower (it was added to Magento in 2.3). However we stopped using it, and in fact it should never have even made it to v1.0.0 of the separate Chat module.

Related work items: #193594, #193596

Controller/Profile/Index.php

@@ -4,16 +4,27 @@
 
 use Dotdigitalgroup\Chat\Model\Profile\UpdateChatProfile;
 use Magento\Framework\App\Action\Context;
-use Magento\Framework\App\ResponseInterface;
-use Magento\Framework\App\Action\Action;
+use Magento\Framework\App\RequestInterface;
+use Magento\Framework\App\Action\HttpPostActionInterface;
+use Magento\Framework\HTTP\PhpEnvironment\Response;
 
-class Index extends Action
+class Index implements HttpPostActionInterface
 {
     /**
      * @var UpdateChatProfile
      */
     private $chatProfile;
 
+    /**
+     * @var Response
+     */
+    private $response;
+
+    /**
+     * @var RequestInterface
+     */
+    private $request;
+
     /**
      * Profile constructor
      *
@@ -25,21 +36,19 @@ public function __construct(
         UpdateChatProfile $chatProfile
     ) {
         $this->chatProfile = $chatProfile;
-        parent::__construct($context);
+        $this->request = $context->getRequest();
+        $this->response = $context->getResponse();
     }
 
     /**
      * Update the user's profile with Chat
      *
-     * @return ResponseInterface
+     * @return Response
      */
-    public function execute()
+    public function execute(): Response
     {
-        $this->chatProfile->update($this->getRequest()->getParam('profileId'));
-        /** @var \Magento\Framework\HTTP\PhpEnvironment\Response $response */
-        $response = $this->getResponse();
-        $response->setHttpResponseCode(204);
-        $response->sendHeaders();
-        return $response;
+        $this->chatProfile->update($this->request->getParam('profileId'));
+        $this->response->setHttpResponseCode(204);
+        return $this->response;
     }
 }