Show also the otpauth:// URI when registering 2FA
2FA can be set up in devices other than mobile phones, e.g. personal computers, where the user needs to set up OTP parameters manually, since it is difficult to scan the QR Code. It would be nice if when registering 2FA gitlab shows the value of the QR Code (that is, the full otpauth:// uri), and not only each value ("details") separately.