change trait `IsDistanceOk` to `CheckDistanceOk`

Right now, the IsDistanceOk trait returns a boolean. This mean that check_idty_allowed_to_claim_membership and check_idty_allowed_to_renew_membership can only return an error like DistanceNotOK which could be improved reflect whether it is DistanceNotAvailable or DistanceKO.

We should change this trait to something like CheckDistanceOk returning a DispatchError instead of a bool.

changed milestone to %Horizon

mentioned in merge request !183 (merged)

May be done after #113 (closed) adds a DistanceKO variant.

added P9-somedaymaybe label

Closed in !200 (merged) (except the renaming)

closed

changed milestone to %runtime-800