runtime: make the candidate relay parent progression check more strict (#5113)

Previously, we were checking if the relay parent of a new candidate does
not move backwards from the latest included on-chain candidate. This was
fine prior to elastic scaling. We now need to also check that the relay
parent progresses from the latest pending availability candidate, as
well as check the progression within the candidate chain in the inherent
data.

Prospective-parachains is already doing this check but we should also
add it in the runtime