Block clipboard UI when device is locked

In some situations (see bug for details) it's possible to enter the
clipboard even while the device is locked, and from there access the
provided intents. Users should not be able to access intents from this
state; this change adds an additional check before showing the interactive UI.

The behavior is identical to what we do when user setup is not complete
(b/251778420): we show a toast to note that content has been copied, but no interactive UI.

Interactive UI is only blocked when device is locked (i.e. requiring pin
entry/password/biometric/etc), not if the keyguard is up but trivially
dismissable.

Bug: 317048495
Test: atest ClipboardListenerTest; verification using steps in linked
bug as well as forcing text content to appear client-side, to verify
that even if text content is received in the ClipboardListener, no
interactive UI appears.

(cherry picked from commit 2976ca86)
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:b9ffec803b31f1b57756105c9fbfd0cb672fcfde)
Merged-In: I1a48cbe64852dce3fba69915ca11dad8878f66eb
Change-Id: I1a48cbe64852dce3fba69915ca11dad8878f66eb