Remove the "Pass widget" config from Settings

Since the Pass widget is an app-specific feature (specifically Baton's),
the option to toggle the widget should be presented in the app's
settings and not in the system settings.

Change-Id: Iec1b4bf4fe25b0d1357c78177f05672c58fe72d3
SECURITY: Don't pass a usable Pending Intent to 3rd parties.

Unfortunately the Settings app has super powers. We shouldn't let
untrusted 3rd party authenticators re-purpose those powers to their own
nefarious ends.  This means that we shouldn't pass along PendingIntents
that can have addressing information (component, action, category)
filled in by third parties.

Bug: 17356824
Change-Id: I397d26c5f465ddfb0e58bbc66cd44756e58cc507
(cherry picked from commit f5d3e74ecc2b973941d8adbe40c6b23094b5abb7)