R1:5a89da12e293

When users have no password on their account, guide them through the "reset password" flow in the guise of "set password"

Summary:
Depends on D20119. Fixes T9512. When you don't have a password on your account, the "Password" panel in Settings is non-obviously useless: you can't provide an old password, so you can't change your password.

The correct remedy is to "Forgot password?" and go through the password reset flow. However, we don't guide you to this and it isn't really self-evident.

Instead…