Settings sync plan for March 2020 milestone

Features

• Synchronise Snippets - Support synchronising Snippets #86678
• Synchronise UI State - Support synchronising global state #86679
• Show previously synced data from server - Settings sync history command #85619

Backlog

Architecture

• Prevent update request when payload is too large - Do not make requests if sync files are too large #89597
• Trace update requests by attaching machine id - [Serviceability] Trace server updates by machine id #90074
• Local Ignored settings - Settings Sync: Ignore a setting locally #89627

Features