gunit: Add unit tests for cgroup_build_tasks_procs_path()

gunit: Add unit tests for cgroup_build_tasks_procs_path()

This commit adds unit tests for cgroup_build_tasks_procs_path()

[----------] 6 tests from BuildTasksProcPathTest
[ RUN      ] BuildTasksProcPathTest.BuildTasksProcPathTest_ControllerNotFound
[       OK ] BuildTasksProcPathTest.BuildTasksProcPathTest_ControllerNotFound (0 ms)
[ RUN      ] BuildTasksProcPathTest.BuildTasksProcPathTest_UnknownCgVersion
[       OK ] BuildTasksProcPathTest.BuildTasksProcPathTest_UnknownCgVersion (0 ms)
[ RUN      ] BuildTasksProcPathTest.BuildTasksProcPathTest_CgV1
[       OK ] BuildTasksProcPathTest.BuildTasksProcPathTest_CgV1 (0 ms)
[ RUN      ] BuildTasksProcPathTest.BuildTasksProcPathTest_CgV2
[       OK ] BuildTasksProcPathTest.BuildTasksProcPathTest_CgV2 (1 ms)
[ RUN      ] BuildTasksProcPathTest.BuildTasksProcPathTest_CgV1WithNs
[       OK ] BuildTasksProcPathTest.BuildTasksProcPathTest_CgV1WithNs (0 ms)
[ RUN      ] BuildTasksProcPathTest.BuildTasksProcPathTest_CgV2WithNs
[       OK ] BuildTasksProcPathTest.BuildTasksProcPathTest_CgV2WithNs (0 ms)
[----------] 6 tests from BuildTasksProcPathTest (1 ms total)

Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>