CBG-4782: new rev tree property for ISGR replications

[gregns1]

CBG-4782

• PR for the transportation of the new rev tree property for ISGR replications
• Nothing is done with it yet this is done in future tickets
• Had to set client type on active peer given this wasn't set before and we need to know if its ISGR to send/receive this property

Pre-review checklist

• Removed debug logging (fmt.Print, log.Print, ...)
• Logging sensitive data? Make sure it's tagged (e.g. base.UD(docID), base.MD(dbName))
• Updated relevant information in the API specifications (such as endpoint descriptions, schemas, ...) in docs/api

Dependencies (if applicable)

• Link upstream PRs - CBG-4780: basic ISGR push and pull for 4.0 #7668 not directly related but would want to rebase this or the other depending on which get merged first to ensure nothing is broken

Integration Tests

• GSI=true,xattrs=true https://jenkins.sgwdev.com/job/SyncGateway-Integration/3244/

[Copilot]

Pull Request Overview

This PR introduces a new revision tree property (revTree) for ISGR (Inter-Sync Gateway Replication) replications to support transportation of revision tree information between Sync Gateway peers. The property is added for future use but not yet processed in the write path.

• Adds new revTree message property constant and handling in BLIP sync messages
• Implements logic to send/receive revision tree property when communicating between SGW peers using version vectors
• Sets client type on active replicator peers to enable proper ISGR communication

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
db/blip_sync_messages.go	Adds new RevMessageTreeHistory constant for the revTree property
db/blip_sync_context.go	Implements logic to send revision tree property and adds helper method
db/blip_handler.go	Adds receiving logic for revision tree property in rev messages
db/blip.go	Updates blipRevMessageProperties function to include revision tree property
db/active_replicator.go	Sets client type to SGR2 for active replicator connections

[Copilot]

[nitpick] This TODO comment explains implementation details rather than intent. Consider replacing with a comment that explains why a separate list is needed for the rev tree property, or reference the specific ticket (CBG-4790) that will address this.