1150 - Fix crash when clicking on Staff without User record

[vladislav-kir]

1. What triggered this change? (PBI link, Email Subject, conversation + reason, etc)

#1150

2. What was changed?

• UserService | CreateUser - Automatically create a Staff record for new Staff users

• UpsertStaffMemberProfileCommandHandler - Automatically create a User record for new Staff records

• Added AchievementHelper | GenerateCode - refactored repeated code for generating Achievement QR Code

3. Did you do pair or mob programming?

No

[jernejk]

Found an interesting bug that would have no impact on the application but was interesting for me to verify that I know the difference between ?? and ??= when it comes to the order of operation. :)

Other than the suggested change, LGTM.