[REQ] cpp-qt-client - in the HttpHelper execute method please keep the request (m_request_content = "") and provide a getter for the request object.

Is your feature request related to a problem? Please describe.

We often fire N REST requests to the REST server in one go, if any of these fail, then it is currently important to know which request has failed. As the request is not stored in the HttpHelper it is not possible to match the error response to the matching request.
What we currently do is edit the second line in the execute() method to keep the request_content. The m_request_content is then added to the header public section. Using the payload helper method fromJson, we can reconstruct the original request payload object.

Describe the solution you'd like

Please keep the request content object inside the HttpHelper class and make it available from the application code.

Describe alternatives you've considered

One workaround is to serially request things, but this takes a long time.
What we do is edit the second line in the execute() method to keep the request_content. The m_request_content is then added to the header. Using the method fromJson, we can reconstruct the original request payload.

Additional context

Start at the cpp-qt-client HttpHelper execute() method and inspect how m_request_content is currently handled. Check the fromJson usage described in the issue and determine how application code can access the retained request object. Done means concurrent requests can be matched to their error responses without serializing them.