#297

Add support for the replace conflict resolution strategy

• to be used on at most one property,
• if Sync is enabled all @Unique properties must use REPLACE strategy (and with above rule at most one can exist).

Tasks

• Check if sync-enabled entity, all unique properties use REPLACE.
• Add tests.
  • build_runner tests seem not possible (e.g. to verify errors on misconfigurations), so tested manually.