Add AD certificate authentication test

[krishnavema]

No description provided.

[gemini-code-assist]

Code Review

This pull request adds a new system test for AD certificate authentication using a virtual smartcard. The changes include updating a test dependency and adding the new test case with a helper function for certificate enrollment. The overall approach is sound, but I've identified one area for improvement to increase test reliability by replacing a fixed sleep with a more robust polling mechanism.

[gemini-code-assist]

Using a fixed time.sleep(5) can lead to flaky tests. If the virt_cacard.service takes longer to start under load, the test might fail. Conversely, if the service starts quickly, the test is unnecessarily delayed. A more robust approach is to poll for the service's status until it becomes active.

Suggested change

	time.sleep(5)
	for _ in range(10):
	result = client.host.conn.run("systemctl is-active --quiet virt_cacard.service", raise_on_error=False)
	if result.rc == 0:
	break
	time.sleep(1)
	else:
	pytest.fail("virt_cacard.service did not become active in time.")