Make the transaction coordinator compute the necessary metadata for "endOfTransaction", persist it in the coordinator document for the transaction, and send it to the participant shards as part of the commitTransaction command. The participant shards currently do not use the additional metadata, but a follow-up PR will make them write the data to their oplog as part of the existing commitTransaction oplog entry.

Computing and sending the metadata is gated on the feature flag for SPM-4826 and on a server parameter (both currently disabled by default).