Add more information to existing notification_* events.

Include calling UID/PID in the existing
notification_{enqueue/cancel/cancel_all} event logs.

Include a new "reason" arg for cancel + cancel_all to
identify listener vs noman vs statusbarmgr calls.

Found and fixed a cancelAll path (from statusbarmgr)
that was not logging at all.

Bug:13442201
Change-Id: I2e1f875076a96b1fe3b86e8990641efb1cadfcfb