ci: add testcase for multi-profile UKIs

ci: add testcase for multi-profile UKIs

This tests the whole shebang:

1. That ukify can generate them properly
2. That systemd-boot can dissect them properly
3. That systemd-stub can accept profile selection propery
4. That the profile information ends up in /run/systemd/stub/ properly
5. That systemd-measure correctly calculates the expected PCR 11 values
   for each profile and that we can unlock a public-key bound LUKS
   volume with it