ftests: Add a test for cgroup_attach_task_pid()

ftests: Add a test for cgroup_attach_task_pid()

Add a functional test for cgroup_attach_task_pid().

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Test Results:
	Run Date:                          Jan 04 21:06:16
	Passed:                                  1 test(s)
	Skipped:                                 0 test(s)
	Failed:                                  0 test(s)
-----------------------------------------------------------------
Timing Results:
	Test                                   Time (sec)
	-------------------------------------------------
	setup                                        0.00
	053-sudo-cgroup_attach_task_pid.py           2.06
	teardown                                     0.00
	-------------------------------------------------
	Total Run Time                               2.06

Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>
Reviewed-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>