Authenticator feature request: Add manually

[elwindewitte]

I know it's not the happy flow, but it might be nice to be able to add the secret key for an account manually if you're not able to scan the QR code. Perhaps it would be just as simple as adding a button in the scanner like this:

Disregard the 'Scan card' title, it's a screenshot from my Wallet tool.

[dupontgu]

Yeah that's a great call. I'll sync with joe on design.