selftests/landlock: Extend tests for landlock_restrict_self(2)'s flags

selftests/landlock: Extend tests for landlock_restrict_self(2)'s flags

Add the base_test's restrict_self_fd_flags tests to align with previous
restrict_self_fd tests but with the new
LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF flag.

Add the restrict_self_flags tests to check that
LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF,
LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON, and
LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF are valid but not the next
bit.  Some checks are similar to restrict_self_checks_ordering's ones.

Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Link: https://lore.kernel.org/r/20250320190717.2287696-22-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>