Add a Continue button when choosing a passphrase. And fix a few other design nits with choosing a password.
Specifically: - Add a Continue button on the passphrase screens - Remove the Skip button on the first passcode screen - Fix phrasing of "4 numbers" to "4 digits only" - When pressing Back on the Wi-Fi screen, go to "Lock security" page instead of the "Choose a password" page.
This branch requires a change in the unity8 Lockscreen component that exposes the passphrase content to us. Thus, I've bumped the required unity8 version. Fixes: 1383702