security/virt_what: add test for expected value

[smitterl]

Since virt-what-1.25-9, there's an additional command 'virt-what-cvm' that gives information about if and which confidential VM mode is running.

The test per default assumes that the VM runs without confidentiality. It can be configured to cover other values depending on the guest. The supported outputs are listed on the man virt-what-cvm.

[smitterl]

Tested on s390x both with normal and SE guest

# avocado run --test-runner runner --vt-type libvirt --vt-machine-type s390-virtio --vt-connect-uri qemu:///system virt_what.cvm
No python imaging library installed. Screendump and Windows guest BSOD detection are disabled. In order to enable it, please install python-imaging or the equivalent for your distro.
No python imaging library installed. PPM image conversion to JPEG disabled. In order to enable it, please install python-imaging or the equivalent for your distro.
JOB ID     : 7839ded3d34b4d1c3030a4d4ac701d2a743260b8
JOB LOG    : /var/log/avocado/job-results/job-2024-08-22T09.29-7839ded/job.log
 (1/1) type_specific.io-github-autotest-libvirt.virt_what.cvm.expected_value: PASS (19.44 s)
Not opening readers, lock_server_running not locked
Not opening readers, lock_server_running not locked
RESULTS    : PASS 1 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0 | CANCEL 0
JOB HTML   : /var/log/avocado/job-results/job-2024-08-22T09.29-7839ded/results.html
JOB TIME   : 19.84 s

# avocado run --test-runner runner --vt-type libvirt --vt-machine-type s390-virtio --vt-connect-uri qemu:///system virt_what.cvm --vt-extra-params "expected_cvm = s390-protvirt"                                                                                                                                                                                              
No python imaging library installed. Screendump and Windows guest BSOD detection are disabled. In order to enable it, please install python-imaging or the equivalent for your distro.
No python imaging library installed. PPM image conversion to JPEG disabled. In order to enable it, please install python-imaging or the equivalent for your distro.
JOB ID     : 9ccfb06cb0abb919230d60e67dad21ded51abf4f
JOB LOG    : /var/log/avocado/job-results/job-2024-08-22T09.28-9ccfb06/job.log
 (1/1) type_specific.io-github-autotest-libvirt.virt_what.cvm.expected_value: PASS (21.04 s)
Not opening readers, lock_server_running not locked                                                       
Not opening readers, lock_server_running not locked                                                       
RESULTS    : PASS 1 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0 | CANCEL 0
JOB HTML   : /var/log/avocado/job-results/job-2024-08-22T09.28-9ccfb06/results.html
JOB TIME   : 21.44 s