Resolve ContextualSearch Activity as the calling user.

While the intent itself is sent by the system which has access to the
screenshots and non-exported activities, we need to resolve the Activity
in the same way that the caller (Launcher) does. Otherwise in HSUM the
activity may not be found by the system user.

Also add additional logs which will help us understand failures.

Bug: 369560470
Flag: EXEMPT bugfix
Test: Manual
Change-Id: I3707f9001143400a3faf29e2dbd35351058382a8