KVM: selftests: Add helper for enabling LPIs on a redistributor

The selftests GIC library presently does not support LPIs. Add a
userspace helper for configuring a redistributor for LPIs, installing
an LPI configuration table and LPI pending table.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240422200158.2606761-18-oliver.upton@linux.dev


Signed-off-by: Marc Zyngier <maz@kernel.org>