provide feedback message on assertions

[RedJocker]

• assertions methods have a version without feedback message and with feedback message, always choose the version that has feedback message
  • feedback messages are really important for users
    • users don't usually keep track of every detail from description, they usually make some changes and then run tests to see feedback and then proceed to do what is missing guided by the feedback
  • feedback messages are really important for maintenance of the project
    • we keep track every single submission for every step
    • when revising submissions error messages are the first thing noticed, and very frequently the only thing noticed since reading solutions take much more time
    • good feedback messages can give a good overview of how are users dealing with stages
    • good feedback messages can indicate points that should have closer attention from mainteners