Master Password migration

[indutny]

Is your feature request related to a problem? Please describe.

In a situation where master password is leaked, it would be helpful if user could copy all apps from old master password to new one.

Describe the solution you'd like

The settings page would have a "Migrate" button that would decrypt old applications and re-encrypt them with new password. Note that old applications are still going to be there to aid the password-change process.

Describe alternatives you've considered

There're no alternatives!

Additional context

And no context :wink: