Add '-P ds' and '-D ds' to dnssec-settime

Add '-P ds' and '-D ds' to dnssec-settime

Add two more arguments to the dnssec-settime tool. '-P ds' sets the
time that the DS was published in the parent, '-D ds' sets the time
that the DS was removed from the parent (these times are not accurate,
but rely on the user to use them appropriately, and as long as the
time is not before actual publication/withdrawal, it is fine).

These new arguments are needed for the kasp system test. We want to
test when the next key event is once a DS is published, and now
that 'parent-registration-delay' is obsoleted, we need a different
approach to reliable test the timings.