SystemUI: support to close all running task in task manager

Add a button in status bar expanded header to switch to task manager,
which supports to watch current running tasks and usage of memory, also
supports to close one or all of running tasks.
CRs-Fixed: 625900

(cherry picked from commit 1a8449b29cff0d245cae6db5d83f8bbc7f9e789a)

Change-Id: I58333514d1580d45a2bffde07a7afc94d5b6d60d