WI: Phase H: Conflict management and local workspace merging support

Note: This is issue is part of #2721129: Workflow Initiative and is only meant for planning and governance sign-offs. Work will happen in child issues of this plan.

Target version: Drupal 8.7+

This phase intend to extend the work done in #2732071: WI: Workspace module roadmap by introducing a richer replication API with conflict management.

Initial plan for a plugin framework: #2688567: Co-maintaining Conflict module for Drupal 8Assigned to: drumm

The merge algorithms needed will use lots of work from this Google Summer of Code project: Solving content conflicts with merge algorithms in Drupal 8. This project resulted in these very useful libraries:

• https://github.com/relaxedws/lca
• https://github.com/relaxedws/merge

Existing and related issues in core:

• #106953: Better handling of editing conflicts

See the Replication, Conflict and Workspace modules for the current reference implementation in contrib.