KVM selftests changes for 6.12:

 - Fix a goof that caused some Hyper-V tests to be skipped when run on bare
   metal, i.e. NOT in a VM.

 - Add a regression test for KVM's handling of SHUTDOWN for an SEV-ES guest.

 - Explicitly include one-off assets in .gitignore.  Past Sean was completely
   wrong about not being able to detect missing .gitignore entries.

 - Verify userspace single-stepping works when KVM happens to handle a VM-Exit
   in its fastpath.

 - Misc cleanups