[Electrum-BTC-BCH-LTC] - Change the 2FA wizard to allow come back if the 2FA app synch is not enable.

[Bastien-Satochip]

[IMPROVEMENT]

When you try to enable the 2FA using the Electrum GUI (BTC, LTC or BCH version), if you are not able to scan the 2FA QR code with your mobile application (Android), you cant revert the action. Meaning your card is now setup with the 2FA. But your mobile app is NOT synch. You cant even revert the configuration because desabling the 2FA require to confirm the action on the mobile phone. In other words, your card is non-usable anymore.

[PROPOSAL]

How about changing the Electrum 2FA wizard to include:

• Either a "BACK" button that will cancel the 2FA configuration;
• Or a "CONFIRMATION" screen after the "Scan the QR code" screen that will prompt the user to confirm that the 2FA app is well configured or not. If YES : continue - and the 2FA is enabled. If NO : revert the 2FA configuration and come back to the initial state.