Back button behaves wrong in keycard multiaccount creation scenarios initiated from the login screen

[guylouis]

When we get in the keycard specific flows from the login screen

Video illustrating this made by Gheorghe available here
https://cdn.discordapp.com/attachments/626364653890437140/676349038521483264/20200210_114902.mp4

Examples:

• login screen/.../generate new key/generate keys/choose chat name/keycard/
• login screen/access key/recover with keycard/begin recovery

then the back button brings systematically too far since it brings back to the onboarding first screen. From which we can't get back to the login screen without killing/opening the app.

Interestingly when we start the same 'recover with keycard flow' from this onboarding screen and not from the login screen the back button behaves well

[guylouis]

tested on nightly form 23/04 and this is solved