libprocessgroup/tools: Add settaskprofile command-line tool

Add a command-line tool to apply task profile(s) to a given thread.

Test: taskprofile $pid ProcessCapacityHigh; grep cpuset /proc/$pid/cgroup
Test: taskprofile $pid ProcessCapacityNormal; grep cpuset /proc/$pid/cgroup
Bug: 204808810
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I1c13731f7a9a1161f36e27436ee104964aacbfd0