Prevent bad intents from crashing sysui

Smartspace could potentially send Intents that don't resolve, which
will crash sysui. Log a warning. Also register an event notifier to
let the SmartspaceSession know of a user action.

Bug: 208350043
Test: atest LockscreenSmartspaceControllerTest + manual (use new
smartspace flashlight off content)

Change-Id: Ife517864c6933bc2d6ef01c28ec97363d9ebfbd7