freeCodeCamp: Show notifications for failed backend project submission

Currently when a backend project submission fails, the users are only notified by a brief warning message saying that the server is not being updated and the user is navigated to the next challenge. as illustrated here https://github.com/freeCodeCamp/freeCodeCamp/issues/37381#issuecomment-544185610

to reproduce:

to make the backend projects submission fail, please add

  componentDidUpdate() {
     this.props.updateSolutionForm({});
  }

below the following block https://github.com/freeCodeCamp/freeCodeCamp/blob/d01ce3bbc11fb0736ed3ad81e8565c6d23c342b9/client/src/templates/Challenges/projects/SolutionForm.js#L30

Additionally this #37494 handles the api side of the message on submission failure, so a JSON should be send to the client upon failure.

expected behavior:

the user should see the message that was sent from the api-server and not be navigated to the next challenge.