move busy interval definition

analysis/abstract/ideal/iw_instantiation.v

analysis/abstract/restricted_supply/iw_instantiation.v

analysis/definitions/busy_interval/classical.v

analysis/definitions/priority_inversion.v

analysis/definitions/sbf/busy.v

analysis/definitions/service_inversion/busy_prefix.v

analysis/definitions/workload/bounded.v

analysis/facts/busy_interval/arrival.v

analysis/facts/busy_interval/quiet_time.v

results/edf/rta/bounded_nps.v

results/fixed_priority/rta/bounded_nps.v