Set package name explicitly when sending copy intent

We broadcast an intent when starting the copy overlay, which is
received by the screenshot process so it knows to dismiss itself.
This causes a warning since sending non-protected broadcasts is
dangerous. Setting the package name explicitly lets
ActivityManagerService determine that the broadcast is safe since
it is only sent within SystemUI.

Bug: 219958007
Fix: 219958007
Test: manual (observed that error message no longer displayed when
copying something to the clipboard)

Change-Id: I1072bf7ebac9d8c761af01a5d888941f8ef24b79