Add SELINUX tests

[vnarapar]

Add below security tests
SELINUX_TEST_Getenforce
SELINUX_TEST_setenforce 0/1
SELINUX_TEST_sestatus
SELINUX_TEST_systemctl list-units --state failed
SELINUX_TEST_AVC Denials
SELINUX_TEST_ls -Zl /usr/bin/, ls -Zl /usr/sbin/
SELINUX_TEST_ls -Zl /dev/
SELINUX_TEST_ps -Zl
SELINUX_TEST_List the modules, Check loading and unloading of .pp files