swatch-contracts ingestion fails on initial contract messages

The partner gateway's initial messages contain subscriptionNumber or the dimensions, but not both at the same time. Contract ingestion should handle this by enriching the missing information from the Partner Gateway APIs before attempted validation.

Namely, ContractService.collectMissingUpStreamContractDetails should be called before ContractService.validPartnerEntitlementContract. Note that because collectMissingUpstreamContractDetails operates on ContractEntity, while validPartnerEntitlementContract operates on PartnerEntitlementContract, that needs to be reconciled (validPartnerEntitlementContract should be refactored to validate a ContractEntity instead).

QE Notes: Should be testable in the integration testing. Messages are currently different than what was initially expected.