Move hook execution decision to HooksMaster

Currently, the HooksMaster creation and execution decision is in the
Processor class. This is not optimal, so we change to always create a
hooks master and instead make the decision inside that class, by
creating empty node lists for both pre and post if the lu doesn't
support hooks. This way, hooks decisions are moved to HooksMaster (where
they belong).

Reviewed-by: imsnah