Add support from authy 2fa windows tool export & firefox tool backup json file

[wazerstar]

<You can also suggest feedback by Tweeting with #AuthenticatorFeedback>

Describe the feature you want:
Before this app got developed for firefox, there was only one known 2fa app that worked good.
https://addons.mozilla.org/da/firefox/addon/two-factor-authenticator/

His string goes like this for import / export.

{"otp_list":[{"name":"Microsoft Dummy Account","key":"XXXXXXX"},{"name":"Google Dummy Account","key":"xxxxxx"}]}

And for authy try it out your self, this way would go export strings via this tool and import them directly from export line.
https://github.com/alexzorin/authy/releases

Why do you want this feature in Authenticator?
Will make it a lot easier and 100% secure and complete without human errors.

[DannyBen]

Now that Authy for Desktop app is going End-of-Life, I would be interested to know if there is any easy migration path for Authy users.