Activity feed: Summary of changes in editing context

[chillu]

Overview

As a content author collaborating on a record with multiple authors, I can tell what I'm about to publish.

Design reference: https://projects.invisionapp.com/dsm/silver-stripe/silver-stripe/folder/components/5c68f96ffb26bb0018525d20

Acceptance Criteria

• I can see when draft changes are available, either on the record itself or on any owned relationships
• I can expand the draft change indicator to view a list of changes on owned relationships
• Each snapshot entry shows the author and date
• The record for the activity as well as actions taken (delete, publish, etc) are clear
• Where an editing UI can be determined for a record, the change list links through
• When editing the record (or changing an owned relationship in the same editing context), the draft changes indicator updates
• If multiple snapshots are created on a single day, they're grouped by day
• If applicable, the date of last publication is shown
• Changes are sorted descending by date
• The implementation works in page and GridField editing contexts

Notes

• This needs to be lazy loaded, can't slow down the editing or saving experience
• Should share a lot of the views with view version snapshots alongside versions