Authenticate via fingerprint or PIN to autofill when the app is locked

[sashei]

Acceptance Criteria

Attempting to autofill with a credential from Lockbox while the app is locked will prompt the DialogFragment with either fingerprint or PIN authentication.

Engineering notes

Documentation

User Authentication

Implementation

This involves adding the setAuthentication call to the FillResponse object when returning from the buildFillResponse method in the LockboxAutofillService.

Possible Gotchas

In order to get a list of potential credentials, the DataStore has to be unlocked, so you will need to capture its lock state before unlocking it, use that state to determine when to add the authentication view in the buildFillResponse method, and lock it again if the authentication step fails.

depends on #214

[jhugman]

@changecourse @nickbrandt

What should we do in the cases of:

• autofill text boxes are detected but domain is not detected,
• domain is detected, but domain isn't matched by a credential we have in the data store?
• lockbox is locked, i.e. authentication is required, but domain isn't matched by a credential we have in the data store.

This feels like we should shell out to a version of the item list + filter; but once an item is selected, we should go back and fill the view in the native view.

I don't think there are stories to cover any of these cases.

[linuxwolf]

@jhugman
I think the answer to all of your questions would be addressed with (recently added) #421. The designs do call for an interface that the user can search for a (better) match, but was not completed when we closed #215.