ftests: Add a test for cgroup_attach_task()

ftests: Add a test for cgroup_attach_task()

Add a functional test for cgroup_attach_task()

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Test Results:
	Run Date:                          Jan 04 21:03:14
	Passed:                                  1 test(s)
	Skipped:                                 0 test(s)
	Failed:                                  0 test(s)
-----------------------------------------------------------------
Timing Results:
	Test                               Time (sec)
	---------------------------------------------
	setup                                    0.00
	052-sudo-cgroup_attach_task.py           0.02
	teardown                                 0.00
	---------------------------------------------
	Total Run Time                           0.02

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