Create a redacted single line view

Currently, a mixed public/private notification bundle looks bad, due to
the public notification using its contracted view, despite only having
space for a single line. This change creates a redacted single line view
for these public views.

Flag: android.app.redact_sensitive_content_notifications_on_lockscreen
Test: atest NotificationRowContentBinderImplTest
Fixes: 352020702

Change-Id: Ic3f966f856258a997b3c7d39a53058bf6e45c2a1