Send PendingIntent for screenshot smart actions

Currently we extract the intent and send that directly, which means
it is sent with SysUI's permissions (which is a security
vulnerability). This change switches to sending the PendingIntent
(with the creator's permissions) instead.

Bug: 159822190
Fix: 159822190
Test: manual (ensured that the smart actions still work)
Change-Id: Ia567272382021d4324974fb7d8c2c01b7e556846